Engine Controls - Self-Diagnostics - 3.5L: Diagnosis Oldsmobile Aurora II

ON-BOARD DIAGNOSTICS

The Malfunction Indicator Light (MIL) is located on the right side of instrument cluster and is displayed as an engine icon. The MIL is controlled by the Powertrain Control Module (PCM) and is used to indicate that the PCM has detected a problem that affects vehicle emissions and a Diagnostic Trouble Code (DTC) is present. When ignition is first turned on, MIL should come on and remain on until engine is started to verify bulb and circuit operation. If MIL does not illuminate at all, diagnose MIL circuits. See MALFUNCTION INDICATOR LIGHT INOPERATIVE under SYSTEM TESTS. The PCM is programmed with test routines that check the operation of the various systems that the PCM controls. Some tests check the internal functions of the PCM. Some tests are run continuously while other tests run only under specific conditions (referred to as code enable criteria). When vehicle is operating within conditions for running a particular test, the PCM checks certain parameters and determines whether or not the values are within an expected range. When conditions for setting the DTC are met, the PCM will store a DTC and, if code is emission related, illuminate the MIL. Some DTCs alert the driver via a message. See CODE TYPES . The PCM also saves data and input parameters when most DTCs are set. This data is stored in FREEZE FRAME and/or FAILURE RECORDS. See FREEZE FRAME and FAILURE RECORDS .

DIAGNOSTIC PROCEDURE

Diagnosis of computerized engine control system should be performed in the following order

1. Ensure all engine systems not related to computer system are operating properly. DO NOT proceed with testing unless all other problems have been repaired. Powertrain diagnostic system check must be performed before using specific Diagnostic Trouble Code (DTC) testing procedure. See «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If no DTCs are present and a driveability problem exists, diagnose by symptom. See appropriate TROUBLE SHOOTING - NO CODES article. After repairs are made, clear DTCs, verify vehicle will enter "closed loop" operation and ensure DTC does not reset.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Diagnostic Trouble Codes (DTC) are retrieved using a Tech 2 scan tool, or other OBD-II compatible scan tool connected to Data Link Connector (DLC). (Scheme 20) DLC is located below left side of instrument panel. To retrieve DTCs, powertrain diagnostic system check must be performed. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK under DIAGNOSTIC SYSTEM CHECKS.

Scheme 20

CLEARING DIAGNOSTIC TROUBLE CODES

Note. Manufacturer does not recommend disconnecting the battery to clear Powertrain Control Module (PCM) memory. Disconnecting battery may or may not clear PCM memory, but other memory system memories will be cleared. On many OBD-II systems, PCM will retain memory for an extended period of time even with battery disconnected.

Using Scan Tool

Using scan tool manufacturer's instructions, clear DTCs. Freeze frame and failure record data will also be cleared. PCM adaptive learning and system monitors will only be cleared for system which had a stored DTC.

Self-Erasure

After 3 consecutive ignition cycles that the diagnostic runs and does not fail, PCM will turn off the malfunction indicator light. At that time, the PCM will automatically switch to a warm-up cycle counter. A warm-up cycle occurs when engine temperature increases 22°F from start-up and reaches a minimum of 160°F (71°C). The PCM will clear DTCs from memory after 40 consecutive warm-up cycles if the recent malfunction does not reoccur in that time.

SCAN TOOL USAGE

Note. OBD-II vehicles have options available in the scan tool DTC mode to display enhanced information available. However, to fully utilize information and procedures requires the use of a Tech 2 scan tool. See scan tool operator's manual for additional information.

Scan Tool Displays

When the scan tool displays a Diagnostic Trouble Code (DTC), the status of the DTC is also displayed. The following are Tech 2 scan tool sub-menus in the DTC INFO and SPECIFIC DTC modes. DTC statuses will be indicated only when they apply to the DTC that is set.

1. FAIL THIS IGN. This selection indicates that this DTC failed during the present ignition cycle.
2. LAST TEST FAIL This selection indicates that this DTC failed the last time the test ran. If type "A" or "B" DTCs are displayed, the last test may have ran during the previous ignition cycle. For type "C" DTCs, the last failure must have occurred during the current ignition cycle to be displayed as LAST TEST FAIL.
3. MIL REQUEST This selection indicates that this DTC is currently requesting MIL illumination. This selection will report type "B" DTCs only after MIL illumination has been requested (failed twice).
4. TEST FAIL SCC Test Fail Since Code Clear (SCC) indicates that this DTC is active since the last time DTCs were cleared.
5. HISTORY This selection indicates that this DTC is stored in the PCM history memory. Type "B" DTCs will not appear in history until they have been requested by the MIL (failed twice). History will display all type "A" and type "B" DTCs that have the MIL illuminated and have failed within the last 40 warm-up cycles. It will also display type "C" DTCs that have failed within the 40 warm-up cycles.
6. NOT RUN SCC Not Run Since Code Clear (SSC) will display DTCs that have not run since DTCs were last cleared. Since any displayed DTCs have not run, their condition (passing or failing) is unknown.

AIR CONDITIONING DIAGNOSTIC SYSTEM CHECK

1. Connect scan tool to Data Link Connector (DLC). DLC is located below left side of instrument panel, on hood release bracket. If scan tool powers up, go to next step. If scan tool does not power up, perform «SCAN TOOL DOES NOT POWER UP»(ref-126121-S36181393302001102400000) under SYSTEM TESTS.
2. Turn ignition on. Using scan tool, attempt to communicate with Driver Door Module (DDM), Powertrain Control Module (PCM), Instrument Panel Integration Module (IPIM) and Dash Integration Module (DIM). If scan tool communicates with DDM, PCM, IPIM and PCM, go to next step. If scan tool does not communicate with DDM, PCM, IPIM and PCM, diagnose communication problem. See SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Using scan tool, select DDM, PCM, IPIM and PCM, display DTCs function. If scan tool displays any DTCs, go to next step. If scan tool does not display any DTCs, repair air conditioning system by symptom. See AUTOMATIC A/C-HEATER SYSTEMS - AURORA article in AIR CONDITIONING & HEATING.
4. If scan tool does not display any DTCs which begin with "U", go to next step. If scan tool displays any DTCs which begin with "U", diagnose communication problem. See SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
5. If scan tool does not display DTC B10XX, go to next step. If scan tool displays DTC B10XX (except B1000), perform appropriate test in accordance with DTC retrieved. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
6. If scan tool displays DTC B1327, repair charging system as necessary. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If scan tool does not display DTC B1327, go to next step.
7. If scan tool displays DTC P0530, P0533, P1536, P1545 or P1546, repair air conditioning system as necessary. See AUTOMATIC A/C-HEATER SYSTEMS - AURORA article in AIR CONDITIONING & HEATING. If scan tool displays any other DTCS, diagnose DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

ENGINE COOLING DIAGNOSTIC SYSTEM CHECK

1. Connect scan tool to Data Link Connector (DLC). (Scheme 20) DLC is located below left side of instrument panel. Turn ignition on. If scan tool powers up, go to next step. If scan tool does not power up, see «SCAN TOOL DOES NOT POWER UP»(ref-126121-S36181393302001102400000) under SYSTEM TESTS.
2. Using scan tool, attempt to communicate with Instrument Panel Cluster (IPC), Dash Integration Module (DIM) and Powertrain Control Module (PCM). If scan tool communicates with IPC, DIM and PCM, go to next step. If scan tool does not communicate with IPC, DIM and PCM, diagnose communication problem. See SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Using scan tool, select IPC, DIM and PCM display DTCs function. If scan tool displays any DTCs, go to next step. If scan tool does not display DTCs, repair engine cooling system by symptom. See ELECTRIC COOLING FANS - CARS article in ENGINE COOLING.
4. If scan tool displays any DTCs that begin with "U", diagnose communication problem. See SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display any DTCs that begin with "U", go to next step.
5. If scan tool displays DTC P1258, P0480 or P0481, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000). If scan tool displays any DTCs that begin with "B", repair DTCs as necessary. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.

ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK

1. Ensure battery is correct battery for vehicle. Ensure battery is fully charged and in good working condition. Replace battery as necessary. If battery is okay, go to next step.
2. Connect scan tool, if not already connected. Turn ignition on. If scan tool powers up, go to next step. If scan tool does not power up, see «SCAN TOOL DOES NOT POWER UP»(ref-126121-S36181393302001102400000) under SYSTEM TESTS.
3. Using scan tool, attempt to communicate with Instrument Panel Cluster (IPC), Dash Integration Module (DIM) and Powertrain Control Module (PCM). If scan tool communicates with IPC, DIM and PCM, go to next step. If scan tool does not communicate with IPC, DIM and PCM, diagnose communication problem. See SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
4. Using scan tool, select IPC, DIM and PCM display DTCs function. If scan tool displays any DTCs, go to next step. If scan tool does not display DTCs, repair charging system by symptom. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.
5. If scan tool displays any DTCs that begin with "U", diagnose communication problem. See SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display any DTCs that begin with "U", go to next step.
6. If scan tool displays DTC B1000, B1007 or B1009, repair as necessary. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display DTC B1000, B1007 or B1009, repair other DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

POWERTRAIN DIAGNOSTIC SYSTEM CHECK

Note. Check for applicable technical service bulletins before proceeding. Do not perform the following procedure if no driveability conditions exists, unless directed here from another procedure. Do not turn ignition off during the following procedure or clear DTCs unless instructed to do so.

1. If vehicle does not crank, see appropriate STARTERS article in STARTING & CHARGING SYSTEMS. Ensure battery is fully charged and cables are clean and tight. Ensure Powertrain Control Module (PCM) grounds are clean, tight, and in proper location. See WIRING DIAGRAMS. PCM is located in engine compartment, inside air filter housing. Install scan tool. If scan tool powers up, go to next step. If scan tool does not power up, see «SCAN TOOL DOES NOT POWER UP»(ref-126121-S36181393302001102400000) under SYSTEM TESTS.
2. Turn ignition on. Attempt to establish communication with PCM, Electronic Brake Control Module (EBCM) and Vehicle Theft Deterrent (VTD) module. If scan tool communicates with all control modules, go to next step. If scan tool does not communicate with all control modules, diagnose communication problem. See SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Attempt to start engine. If engine starts and idles, go to next step. If engine does not start and idle, diagnose engine cranks, but does not start. See NO-START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
4. Using scan tool, select DTC display function for PCM, EBCM and VTD. If any DTCs are present, record DTCs, which module set the DTC and failure record for DTC. Go to next step. If no DTCs are present, go to step 8 .
5. If scan tool displays any DTCs that begin with "U", diagnose communication problem. See SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If scan tool does not display any DTCs that begin with "U", go to next step.
6. If scan tool displays DTC P0601, P0602, P0603, P0604, P0606 or P1621, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not display DTC P0601, P0602, P0603, P0604, P0606 or P1621, go to next step.
7. If scan tool displays DTC P0560, P0562, P0563, P0621 or P0622, see appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If scan tool does not display DTC P0562, P0563, P0621 or P0622, diagnose any other DTCs that are present. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .
8. If customer's concern is with the automatic transmission, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS. If customer's concern is not with the automatic transmission, go to next step.
9. If customer's concern is MIL inoperative, diagnose MIL circuits. See «MALFUNCTION INDICATOR LIGHT INOPERATIVE»(ref-126121-S23533880942001102400000) under SYSTEM TESTS. If customer's concern is MIL always on, diagnose MIL circuits. See «MALFUNCTION INDICATOR LIGHT ALWAYS ON»(ref-126121-S09291357812001102400000) under SYSTEM TESTS. If customer's concern is a driveability problem, diagnose by symptom. See appropriate TROUBLE SHOOTING - NO CODES article.

Diagnostic Procedures

1. Perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. If DTC or driveability concern was repaired using powertrain diagnostic system check, go to step 3 . If no DTC or driveability concern was repaired using powertrain diagnostic system check, go to next step.
2. Check for applicable Technical Service Bulletins (TSB) for software updates that may prevent Inspection/Maintenance (I/M) readiness. Perform any reprogramming or repairs indicated by TSBs. If reprogramming or repair service was required, go to «INSPECTION/MAINTENANCE COMPLETE SYSTEM SET PROCEDURE»(ref-126121-S04311388132001102400000) . If reprogramming or repair service was not required, go to next step.
3. Using scan tool, observe I/M system status display. If more than one test indicates a NO status, go to «INSPECTION/MAINTENANCE COMPLETE SYSTEM SET PROCEDURE»(ref-126121-S04311388132001102400000) . If only one test indicates a NO status, perform appropriate I/M system set procedure for indicated system. See «INSPECTION/MAINTENANCE SYSTEM SET PROCEDURE INDEX»(ref-126121-S34613595252001102400000) table. INSPECTION/MAINTENANCE SYSTEM SET PROCEDURE INDEX System With NO Status Perform AIR System «INSPECTION/MAINTENANCE AIR SYSTEM SET PROCEDURE»(ref-126121-S18291509882001102400000) Catalyst System «INSPECTION/MAINTENANCE CATALYST SYSTEM SET PROCEDURE»(ref-126121-S31355129162001102400000) EGR System «INSPECTION/MAINTENANCE EXHAUST GAS RECIRCULATION SYSTEM SET PROCEDURE»(ref-126121-S41856347142001102400000) EVAP System «INSPECTION/MAINTENANCE EVAPORATIVE EMISSION SYSTEM SET PROCEDURE»(ref-126121-S07817932182001102400000) HO2S/O2S System «INSPECTION/MAINTENANCE HEATED OXYGEN SENSOR/OXYGEN SENSOR SYSTEM SET PROCEDURE»(ref-126121-S22705861352001102400000) HO2S Heater System «INSPECTION/MAINTENANCE HEATED OXYGEN SENSOR HEATER SYSTEM SET PROCEDURE»(ref-126121-S13540324632001102400000)

Diagnostic Aids

I/M system status display provides an indication of when control module has completed required tests. This does not necessarily mean that test has passed, only that test has run. If diagnostics fail, a DTC will indicate failure. If a failure indication is present for a DTC associated with one of the I/M regulated systems, it may prevent other required tests from running. I/M system status information may be useful for a technician to determine if diagnostics have run when verifying repairs.

Note. Before performing this procedure, read diagnostic aid information. See DIAGNOSTIC AIDS .

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(ref-126121-S12749405482001102400000) . NOTE: Whenever ignition is on, ignition voltage is supplied to Heated Oxygen Sensor (HO2S) heaters. After verifying enable criteria, turn ignition off for approximately 5 minutes to allow sensors to cool before continuing test. Once engine is started, DO NOT turn engine off for remaining portion of procedure.
2. Program scan tool with vehicle information before ignition is turned on. Turn off all accessories, including A/C and blower fan. Set vehicle parking brake. Ensure transmission is in Park. Ensure vehicle meets conditions for running this procedure. See «ENABLE CRITERIA»(ref-126121-S18495838612001102400000) . Start engine. Allow engine to idle. Allow engine to idle for 2 minutes. Go to next step.
3. Test drive vehicle. Ensure vehicle is accelerated at part throttle to 55 MPH. Drive vehicle at 55 MPH until engine reaches normal operating temperature. This may take 8-10 minutes depending on start-up coolant temperature. Continue test driving vehicle under these conditions for 6 minutes. Go to next step.
4. Reduce vehicle speed to 45 MPH, maintain this speed for one additional minute. Perform 4 decelerations of 25 seconds each from 45 MPH while maintaining the following criteria: Throttle is closed. No brake application. No manual downshift. Vehicle speed remains greater than 25 MPH. After each deceleration period, vehicle speed is returned to 45 MPH under part throttle acceleration and speed is maintained for 15 seconds. Go to next step.
5. Accelerate vehicle at part throttle to 45-55 MPH. Maintain this speed for 2 minutes. Decelerate vehicle to zero MPH. Idle engine for 2 minutes while service brake is depressed and transmission is in Drive. Go to next step.
6. Using scan tool, observe I/M system status display. If all I/M system status indicators updated to YES, go to next step. If any I/M system status indicator did not update to YES, repeat procedure.
7. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate emission related DTCs, system is okay.

Rough road conditions may prevent some tests from running. Extreme high or low ambient temperatures may prevent tests such as HO2S heater and evaporative emission system from initiating. If step is interrupted before completion, perform remaining portion of test procedures. Any portion of test procedure that requires the engine at operating temperature may be repeated. This allows most diagnostics to run and the remaining tests can be performed using individual system set procedures.

If vehicle has recently run, start this procedure at step 3 . This will allow the tests that require engine at operating temperature to run. Using this method allows shorter cool down periods if the tests requiring a cold start do not initiate.

Scan tool can be used to monitor each I/M system status indicator. When all indicators for a test step have updated to YES, testing can move on to next step even if remaining portion of the test is not complete. For example, step 3 is designed to run EVAP, AIR, and HO2S tests. The procedure instructs technician to operate the vehicle in enable conditions for 6 minutes. If all 3 tests have updated to YES within 4 minutes, you do not need to continue with the enable conditions and testing can advance to the next step.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(ref-126121-S12749405482001102400000) .
2. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(ref-126121-S14946121702001102400000) . Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle for 2 minutes. Accelerate at part throttle to 45 MPH and maintain speed for 3 minutes or until or until I/M system status indicator updates to YES. Using scan tool, monitor I/M system status display. If AIR system status updates to YES, go to step 5 . If AIR system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0410, P1415 and P1416 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If AIR system status updated to YES, go to next step. If AIR system status did not update to YES, see «DIAGNOSTIC AIDS»(ref-126121-S25253213762001102400000) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any emission related DTCs, system is okay.

The AIR pump generally operates once per ignition cycle, usually upon initial start-up before the engine goes into closed loop fuel control. Some systems will perform a passive diagnostic test at this time. The active diagnostic test is performed after the engine goes into closed loop fuel control. On vehicles that perform a passive test, the active test will only run if the passive test fails or is intermittent. The active test may not run if the passive test passes.

I/M system status does not indicate whether test has passed or failed, only that test has run. When all diagnostics for a specific system have run and passed, I/M system status will update to YES. If a test for a specific system has failed, I/M system status will update to YES, indicating a determination was made, even if all required tests have not run. When a failure occurs, DTC emission related DTC portion of the I/M system status display will indicate malfunction indicator light is requested. I/M system status also registers number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(ref-126121-S12749405482001102400000) .
2. Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle. Accelerate at part throttle to 55 MPH and maintain speed for 5 minutes. Decelerate to a stop. Allow engine to idle for 2 minutes with service brake applied and transmission in Drive. Using scan tool, monitor I/M system status display. If CATALYST system status updates to YES, go to step 5 . If CATALYST system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, monitor DTC P0420. Operate vehicle within code enable criteria for DTC P0420. See «DTC P0420: CATALYST SYSTEM LOW EFFICIENCY»(ref-126121-S28196098822001102400000) under DIAGNOSTIC TESTS. Operate vehicle within code enable criteria until scan tool indicates diagnostic test has run. Using scan tool, observe I/M system status display. If CATALYST system status updates to YES, go to next step. If CATALYST system status did not update to YES, see «DIAGNOSTIC AIDS»(ref-126121-S39521003082001102400000) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any emission related DTCs, system is okay.

The PCM runs a maximum of 6 tests per trip until the catalyst system status updates to YES. If the status does not update, the test outlined in this procedure can be repeated until the I/M system status updates to YES. The I/M system status does not indicate whether the test has passed or failed, only that a decision was made. When all of the diagnostics for a specific system have run and passed, the I/M system status updates to YES. If a test for a specific system has failed, the I/M system status updates to YES, indicating a determination was made, even if all of the required tests have not run. When a failure occurs, the emission related DTC portion of the I/M system status display indicates the malfunction indicator light is requested. The I/M system status also registers the number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(ref-126121-S12749405482001102400000) .
2. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(ref-126121-S13018121232001102400000) . Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle. Accelerate at part throttle to 45 MPH and maintain speed for one minute. Perform 4 decelerations of 25 seconds each from 45 MPH while maintaining the following criteria: Throttle is closed. No brake application. No manual downshift. Vehicle speed remains greater than 25 MPH. After each deceleration period, vehicle speed is returned to 45 MPH under part throttle acceleration and speed is maintained for 15 seconds. Using scan tool, observe I/M system status display. If EGR system status updates to YES, go to step 5 . If EGR system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0401, P0404, P0405 and P1404 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If EGR system status updated to YES, go to next step. If EGR system status did not update to YES, see «DIAGNOSTIC AIDS»(ref-126121-S40065160182001102400000) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any emission related DTCs, system is okay.

Powertrain control module only runs the EGR active tests during a gradual deceleration with a closed throttle and with vehicle speed greater than 25 MPH. Several deceleration cycles may be necessary in order to accumulate a sufficient number of EGR flow samples. This procedure is for a clear, flat road. If procedure is performed on a road with a slight downhill grade, the test may acquire the necessary sample counters in one or 2 decel trips. If the test is interrupted during the procedure, it may take more than 10 deceleration cycles in order to complete the test. If the status does not update, the test outlined in this procedure can be repeated until the I/M system status updates to YES.

I/M system status does not indicate whether test has passed or failed, only that test has run. When all diagnostics for a specific system have run and passed, I/M system status will update to YES. If a test for a specific system has failed, I/M system status will update to YES, indicating a determination was made, even if all required tests have not run. When a failure occurs, DTC emission related DTC portion of the I/M system status display will indicate malfunction indicator light is requested. I/M system status also registers number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(ref-126121-S12749405482001102400000) .
2. Using a scan tool, select SPECIAL FUNCTIONS. Determine if vehicle is equipped with a SERVICE BAY TEST for EVAP System. If vehicle equipped with EVAP SERVICE BAY TEST, go to next step. If vehicle is not equipped with EVAP SERVICE BAY TEST, go to step 5 .
3. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(ref-126121-S01533290602001111200000) . Turn off all accessories, including A/C and blower fan. Follow scan tool instructions and perform EVAP SERVICE BAY TEST. If EVAP system passed SERVICE BAY TEST, go to step 8 . If EVAP system did not pass SERVICE BAY TEST, go to next step.
4. Observe scan tool SERVICE BAY TEST for an indication of why test did not pass. Example, a failed DTC or test aborted. Refer to appropriate service information for diagnosis and repair of condition as necessary. After repairs, perform «INSPECTION/MAINTENANCE COMPLETE SYSTEM SET PROCEDURE»(ref-126121-S04311388132001102400000) .
5. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(ref-126121-S01533290602001111200000) . Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle. Operate vehicle under the following conditions: Acceleration at part throttle to 45 MPH. Maintain this speed until engine reaches normal operating temperature. This may take 8-10 minutes depending on start-up coolant temperature. Continue the operating conditions for an additional 3 minutes after engine reaches normal operating temperature, or until I/M system status indicator updates to YES. If EVAP system status updates to YES, go to step 8 . If EVAP system status does not update to YES, go to next step.
6. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any failed DTCs, go to next step.
7. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0440, P0442, P0446 and P1441 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If EVAP system status updated to YES, go to next step. If EVAP system status did not update to YES, see «DIAGNOSTIC AIDS»(ref-126121-S24806395582001102400000) .
8. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any emission related DTCs, system is okay.

Extreme high or low ambient temperatures may prevent EVAP system tests from initiating. Performing a visual inspection prior to running test may prevent having to repeat test. A loose fuel cap may cause test to abort or fail and prevent I/M system from updating. A failed or aborted test will require vehicle to cool down in order to meet enable criteria to run another test.

I/M system status does not indicate whether test has passed or failed, only that test has run. When all diagnostics for a specific system have run and passed, I/M system status will update to YES. If a test for a specific system has failed, I/M system status will update to YES, indicating a determination was made, even if all required tests have not run. When a failure occurs, DTC emission related DTC portion of the I/M system status display will indicate malfunction indicator light is requested. I/M system status also registers number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(ref-126121-S12749405482001102400000) .
2. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(ref-126121-S42801337652001102400000) . Turn off all accessories, including A/C and blower fan. Start engine and allow it to idle. Accelerate at part throttle to 45-55 MPH and maintain speed for 6 minutes or until I/M system status updates to YES. Using scan tool, observe I/M system status. If HO2S/O2S system status updated to YES, go to step 5 . If HO2S/O2S system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0133, P0140, P1133 and P1134 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If HO2S/O2S system status updated to YES, go to next step. If HO2S/O2S system status did not update to YES, see «DIAGNOSTIC AIDS»(ref-126121-S32479081592001102400000) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any emission related DTCs, system is okay.

If status does not update, test outlined in this procedure can be repeated until I/M system status updates to YES.

I/M system status does not indicate whether test has passed or failed, only that test was run. When all diagnostics for a specific system have run and passed, I/M system status will update to YES. If a test for a specific system has failed, I/M system status will update to YES, indicating a determination was made, even if all required tests have not run. When a failure occurs, DTC portion of the I/M system status display will indicate malfunction indicator light is requested. I/M system status also registers number of DTCs.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If there is an impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not run after numerous attempts and no DTC is set, review appropriate scan tool data list and service information for an indication of why test does not complete. Some tests may abort due to changes in conditions while test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning on, may cause test to abort.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

1. If I/M system check has been performed, go to next step. If I/M system check has not been performed, go to «INSPECTION/MAINTENANCE SYSTEM CHECK»(ref-126121-S12749405482001102400000) .
2. Preprogram scan tool with vehicle information before ignition is turned on. Ensure vehicle is operating with conditions for running this procedure. See «ENABLE CRITERIA»(ref-126121-S30389790222001102400000) . Turn off all accessories, including A/C and blower fan. Set vehicle parking brake. Verify transmission is in Park. Start engine and allow it to idle for 2 minutes or until I/M system status indicator updates to YES. If HO2S heater system status updates to YES, go to step 5 . If HO2S heater system status did not update to YES, go to next step.
3. Using scan tool, observe DTC information. If scan tool indicates any failed DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any failed DTCs, go to next step.
4. Using scan tool, observe NOT RAN SINCE CODE CLEARED display to determine if DTCs P0135 and P0141 have run. For those DTCs that have not run, operate vehicle under conditions to meet code enable criteria until DTC(s) runs. See CODE ENABLE CRITERIA under appropriate DTC under DIAGNOSTIC TESTS. Using scan tool, observe I/M system status display. If HO2S heater system status updated to YES, go to next step. If HO2S heater system status did not update to YES, see «DIAGNOSTIC AIDS»(ref-126121-S05598221682001102400000) .
5. Using scan tool, observe emission related DTC portion of I/M system status display. If scan tool indicates any emission related DTCs, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If scan tool does not indicate any emission related DTCs, system is okay.

HO2S heater tests will normally run within 2 minutes allotted in procedure. If there is impending failure, system may require more time to run diagnostic than was allotted in set procedure. If test does not update within allotted period of time, continue operation within enable conditions until test updates to YES. If test does not update to YES, it may have failed or aborted due to loss of enabling conditions. Extremely high ambient temperatures may prevent HO2S heater test from initiating.

First failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update I/M system status to YES. A second trip is required, and all conditions to run must be met in order for test to run again. These conditions may include a partial or complete engine cool down. I/M system status will update only when DTC fails second time, or if all tests pass.

If a diagnostic test is difficult to run, observe I/M system status display while maintaining necessary enable conditions until system status updates to YES.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

Note. Use of Tech 2 scan tool is required to retrieve DTCs. Refer to user reference manual supplied with scan tool.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

1. Check for an open or short to ground in Orange wire between ground and terminal No. 16 at Data Link Connector (DLC). (Scheme 20) If an open or short to ground does not exist, go to next step. If an open or short to ground exists, repair wiring harness as necessary. After repair is complete, perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Check for an open in Black wire between ground and terminal No. 4 at DLC. If an open does not exist, go to next step. If an open exists, repair wiring harness as necessary. After repair is complete, perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
3. Inspect terminals No. 4 (Black wire) and No. 16 (Orange wire) at DLC for poor connections. If connections are okay, go to next step. If poor connections are found, repair as necessary. After repair is complete, perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
4. Scan tool may be faulty. See scan tool manufacturer's user guide. Obtain a known-good scan tool. Perform «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.

Fuse No. 4 (ALDL fuse) in rear fuse block supplies power to DLC terminal No. 16 (Orange wire). Rear fuse block is located underneath driver's side rear seat. If DLC voltage and ground circuits are functioning properly, malfunction must be due to scan tool or scan tool cables.

DIAGNOSTIC TESTS

Note. Before clearing DTCs, perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK under DIAGNOSTIC SYSTEM CHECKS. Record FREEZE FRAME and FAILURE RECORDS for reference during testing. Data will be erased when DTCs are cleared.

Note. If Powertrain Control Module (PCM) is replaced, new PCM must be programmed. See PROGRAMMING .

Note. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold.

Scheme 21

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine and allow idle to stabilize for about one minute. Ensure engine is at normal operating temperature. Using scan tool, monitor HO2S heater current. If current is.45-.65 amp, see «DIAGNOSTIC AIDS»(ref-126121-S36838567752001102600000). If current is not.45-.65 amp, go to next step.
3. Turn ignition off. Remove and inspect fuse No. 20 (OXY SEN fuse) from underhood fuse block. If fuse is blown, go to step 11. If fuse is okay, reinstall fuse and go to next step.
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Turn ignition on. Using a test light connected to ground, probe terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) If test light illuminates, go to next step. If test light does not illuminate, go to step 7.
5. Connect a test light between terminal "C" (Black/White wire) and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. Start engine. If test light illuminates, go to step 9. If test light does not illuminate, go to next step.
6. Turn ignition off. Connect a test light between ground and terminal "C" (Black/White wire) at HO2S bank 1 sensor 1 harness connector. Start engine. If test light illuminates, go to step 8. If test light does not illuminate, go to step 9.
7. Turn ignition off. Repair open in Pink/White wire between fuse No. 20 (OXY SEN fuse) in underhood fuse block and HO2S bank 1 sensor 1. After repairs, go to step 14.
8. Turn ignition off. Repair short to voltage in Black/White wire between HO2S bank 1 sensor 1 and terminal No. 37 at PCM C2 harness connector. see scheme 2 After repairs, go to step 14.
9. Check for poor connections at HO2S bank 1 sensor 1 connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to next step.
10. Replace HO2S bank 1 sensor 1. After repairs, go to step 14.
11. Repair short to ground in Pink/White wire between fuse No. 20 (OXY SEN fuse) in underhood fuse block and HO2S bank 1 sensor 1. After repairs, go to step 14.
12. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to next step.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and for poor terminal-to-wire connections. Inspect wiring harness for damage. If harness appears to be okay, observe scan tool while moving connectors and wiring harnesses related to HO2S bank 1 sensor 1. A change in scan tool display will indicate malfunction location. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since diagnostic test last failed may help to diagnose the condition. The information may help determine how often condition that set the DTC occurs.

Scheme 22

Note. HO2S bank 1 sensor 2 is located behind catalytic converter.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine and allow it to reach normal operating temperature. Using scan tool, clear DTCs. Recheck for DTCs. If DTC P0036 resets, go to next step. If DTC P0036 does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S24440818682001102600000).
3. Turn ignition off. Remove and inspect fuse No. 20 (OXY SEN fuse) from underhood fuse block. If fuse is blown, go to step 13. If fuse is okay, reinstall fuse and go to next step.
4. Turn ignition on. Raise and support vehicle. Remove HO2S bank 1 sensor 2 wiring harness heat shield. HO2S bank 1 sensor 2 is located behind catalytic converter. Disconnect HO2S bank 1 sensor 2. Using a test light connected to ground, probe terminal "D" (Pink/Black wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 21) If test light illuminates, go to next step. If test light does not illuminate, go to step 8.
5. Connect a test light between terminal "C" (Black/White wire) and terminal "D" (Pink/Black wire) at HO2S bank 1 sensor 2 harness connector. Start engine. If test light illuminates, go to next step. If test light does not illuminate, go to step 7.
6. Turn ignition off. Ensure test light is still connected between terminal "C" (Black/White wire) and terminal "D" (Pink/Black wire) at HO2S bank 1 sensor 2 harness connector. Turn ignition on. If test light illuminates, go to step 9. If test light does not illuminate, go to step 11.
7. Turn ignition off. Connect a test light between ground and terminal "C" (Black/White wire) at HO2S bank 1 sensor 2 harness connector. Turn ignition on. If test light illuminates, go to step 10. If test light does not illuminate, go to step 9.
8. Turn ignition off. Repair open in Pink/Black wire between fuse No. 20 (OXY SEN fuse) in underhood fuse block and HO2S bank 1 sensor 2. After repairs, go to step 16.
9. Turn ignition off. Check for an open or short to ground in Black/White wire between HO2S bank 1 sensor 2 and terminal No. 48 at PCM C2 harness connector. see scheme 2 If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to 14
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 48 (Black/White wire) at PCM C2 harness connector. see scheme 2 If any voltage is indicated, repair short to voltage in Black/White wire between PCM and HO2S bank 1 sensor 2. After repairs, go to step 16. If no voltage is indicated, go to 14.
11. Check for poor connections at HO2S bank 1 sensor 2 connector. Repair connector as necessary. After repairs, go to step 16. If connector is okay, go to next step.
12. Replace HO2S bank 1 sensor 2. After repairs, go to step 16.
13. Repair short to ground in Pink/Black wire between fuse No. 20 (OXY SEN fuse) in underhood fuse block and HO2S bank 1 sensor 2. After repairs, go to step 16.
14. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 16. If connectors are okay, go to next step.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and for poor terminal-to-wire connections. Inspect wiring harness for damage. If harness appears to be okay, observe scan tool while moving connectors and wiring harnesses related to HO2S bank 1 sensor 2. A change in scan tool display will indicate malfunction location. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since diagnostic test last failed may help to diagnose the condition. The information may help determine how often condition that set the DTC occurs.

Check for sticking throttle plate. Check for carbon build-up on throttle plate and throttle bore. Unmetered air entering the engine may cause this DTC to set. Ensure oil dipstick is fully seated and oil filler cap is secure. Check for misrouted or damaged MAF sensor wiring harness. Ensure harness is not close to high-voltage components. Check for non-factory or aftermarket add-on devices.

Scheme 23

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine. Using scan tool, check MAF sensor frequency parameter. If frequency reading is 1200 Hz or more, go to next step. If frequency reading is less than 1200 Hz, go to step 4.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S06262057622001102400000).
4. Turn ignition off. Check fuse No. 11 (IGN 1 fuse) in underhood fuse block. If fuse is okay, go to next step. If fuse is blown, go to step 14.
5. Disconnect MAF sensor connector. MAF sensor is located in top of air filter housing. Turn ignition on. Measure voltage between ground and terminal "A" (Yellow wire) at MAF sensor harness connector. (Scheme 23) If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 8.
6. Turn ignition off. Connect a 3-amp fused jumper wire between ground and terminal "A" (Yellow wire) at MAF sensor harness connector. Start engine. Using scan tool, check if any other DTCs set. If any other DTCs are set, go to step 16. If no other DTCs are set, go to next step.
7. Turn ignition off. Connect a test light between terminal "C" (Pink wire) and terminal "B" (Black/White wire) at MAF sensor harness connector. Turn ignition on. If test light illuminates, go to step 18. If test light does not illuminate, go to step 11.
8. If voltage measured in step 5 is less than 4.5 volts, go to step 12. If voltage measured in step 5 is not less than 4.5 volts, go to next step.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "A" (Yellow wire) at MAF sensor harness connector. If no voltage is indicated, go to step 10. If any voltage is indicated, go to step 15.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for continuity between terminal No. 69 (Yellow wire) at PCM C1 harness connector and all other terminals at both PCM C1 and C2 harness connectors. see scheme 2 If continuity exists between any terminals, go to step 17. If continuity does not exist between any terminals, go to step 19.
11. Using a test light connected to ground, probe terminal "C" (Pink wire) at MAF sensor harness connector. If test light illuminates, go to step 13. If test light does not illuminate, go to step 14.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in Yellow wire between terminal "A" at MAF sensor harness connector and terminal No. 69 at PCM C1 harness connector. see scheme 2and (Scheme 23). Also check if Yellow wire at terminal "A" is shorted to Black/White wire at terminal "B" at MAF sensor harness connector. If Yellow wire is open, shorted to ground or shorted to Black/White wire, repair wiring as necessary. After repairs, go to step 22. If wiring is okay, go to step 19.
13. Repair open or high resistance in Black/White wire between ground and terminal "B" at MAF sensor harness connector. See WIRING DIAGRAMS article. After repairs, go to step 22.
14. Check for an open or short to ground in Pink wire between underhood fuse block and terminal "C" at MAF sensor harness connector. Also check fuse No. 11 (IGN 1 fuse) in underhood fuse block. If any problems are found, repair as necessary. After repairs, go to step 22. If no problems are found, go to step 20.
15. Repair short to voltage in Yellow wire between PCM and MAF sensor. After repairs, go to step 22.
16. Repair short between Yellow wire at MAF sensor harness connector and circuit for which DTC was set. See WIRING DIAGRAMS article. After repairs, go to step 22.
17. Repair circuits that are shorted together. After repairs, go to step 22.
18. Check for poor connections at MAF sensor connector. Repair connector as necessary. After repairs, go to step 22. If connector is okay, go to step 20.
19. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 22. If connectors are okay, go to step 21.
20. Replace MAF sensor. After repairs, go to step 22.
21. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
22. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
23. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Low minimum air rate may cause this DTC to set. Check for plugged or misaligned intake air duct. Check for dirty air filter. Check for objects blocking MAF sensor air inlet screen. Any unmetered air entering engine may also cause this DTC to set. Ensure oil dipstick is fully seated and oil filler cap is secure. Check for misrouted or damaged MAF sensor wiring harness. Ensure harness is not close to high-voltage components.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S27085193192001102400000) .
3. Turn ignition off. Disconnect MAF sensor connector. MAF sensor is located in top of air filter housing. Start engine. Using scan tool, check MAF sensor frequency parameter. If frequency reading is zero Hz, go to step 5 . If frequency reading is not zero Hz, go to next step.
4. Check MAF sensor wiring harness for incorrect routing near ignition control modules, solenoids, relays or motors. If any problems are found, reroute wiring harness as necessary. After repairs, go to step 9 . If no problems are found, go to step 6 .
5. Check for poor connections at MAF sensor connector. Repair connector as necessary. After repairs, go to step 9 . If connector is okay, go to step 7 .
6. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 9 . If connectors are okay, go to step 8 .
7. Replace MAF sensor. After repairs, go to step 9 .
8. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . After repairs, go to next step.
9. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
10. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

Water entering air intake system that reaches MAF sensor could cause this DTC to set. Water rapidly cools the hot sensing elements in the MAF sensor causing a false indication of excessive airflow. Check for evidence of water intrusion in the secondary air injection system and the air induction system. Check for faulty connections at MAF sensor connector.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine. Using scan tool, check for any other DTCs that are set. If DTC P1635 is not set, go to next step. If DTC P1635 is set, go to «DTC P1635: 5-VOLT REFERENCE "A" CIRCUIT»(ref-126121-S35998884072001102400000).
3. Using scan tool, observe MAP sensor voltage. If voltage is less than.1 volt, go to step 5. If voltage is.1 volt or more, go to next step.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S06990854402001102400000).
5. Turn ignition off. Disconnect MAP sensor connector. see scheme 6 Turn ignition on. Measure voltage between ground and Gray wire at MAP sensor harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 7.
6. Connect a 3-amp fused jumper wire between Gray and Light Green wires at MAP sensor harness connector. Using scan tool, observe MAP sensor voltage. If voltage is about 5 volts, go to step 9. If voltage is not about 5 volts, go to step 8.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in Gray wire between MAP sensor harness connector and terminal No. 10 at PCM C1 harness connector. see scheme 2 If an open or short to ground exists, repair wiring as necessary. After repairs, go to step 13. If an open or short to ground does not exist, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in Light Green wire between MAP sensor harness connector and terminal No. 25 at PCM C2 harness connector. see scheme 2 If an open or short to ground exists, repair wiring as necessary. After repairs, go to step 13. If an open or short to ground does not exist, go to step 10.
9. Check for poor connections at MAP sensor connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to step 11.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 13. If connectors are okay, go to step 12.
11. Replace MAP sensor. After repairs, go to step 13.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Check MAP sensor vacuum source for leaks, restrictions or poor connections. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine. Using scan tool, check for any other DTCs that are set. If DTC P1635 is not set, go to next step. If DTC P1635 is set, go to «DTC P1635: 5-VOLT REFERENCE "A" CIRCUIT»(ref-126121-S35998884072001102400000). NOTE: If engine idle is rough, unstable or incorrect, correct idle condition before continuing with this test. See SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Using scan tool, observe MAP sensor voltage. If voltage is 4.2 volts, go to step 5. If voltage is not 4.2 volts, go to next step.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S19172240602001102400000).
5. Turn ignition off. Disconnect MAP sensor connector. see scheme 6 Turn ignition on. Using scan tool, observe MAP sensor voltage. If voltage is less than.1 volt, go to next step. If voltage is.1 volt or more, go to step 8.
6. Measure voltage between Gray and Orange/Black wires at MAP sensor harness connector. If voltage is 4.7-5.2 volts, go to step 11. If voltage is not 4.7-5.2 volts, go to next step.
7. If voltage was more than 5.2 volts in previous step, go to step 10. If voltage was less than 4.7 volts in previous step, go to step 9.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Light Green wire at MAP sensor harness connector. If any voltage is indicated, repair wiring as necessary. After repairs, go to step 15. If no voltage is indicated, go to step 12.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Orange/Black wire between MAP sensor harness connector and terminal No. 13 at PCM C1 harness connector. see scheme 2 If continuity does not exist, repair open in Orange/Black wire. After repairs, go to step 15. If continuity exists, go to step 12.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Gray wire at MAP sensor harness connector. If any voltage is indicated, repair wiring as necessary. After repairs, go to step 15. If no voltage is indicated, go to step 12.
11. Check for poor connections at MAP sensor connector. Repair connector as necessary. After repairs, go to step 15. If connector is okay, go to step 13.
12. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 15. If connectors are okay, go to step 14.
13. Replace MAP sensor. After repairs, go to step 15.
14. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
15. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
16. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Check MAP sensor vacuum source for leaks, restrictions or poor connections. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, observe IAT sensor temperature. If temperature reading is more than 266°F (130°C), go to step 4. If temperature reading is 266°F (130°C) or less, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S25700507382001102400000).
4. Turn ignition off. Disconnect IAT sensor connector. IAT sensor is located in air intake passage of engine air induction system and has a 2-pin connector with Tan and Red/Black wires. Turn ignition on. Using scan tool, observe IAT sensor temperature. If temperature reading is about -36°F (-38°C), go to step 6. If temperature reading is not about -36°F (-38°C), go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for short to ground in Tan wire between IAT sensor harness connector and terminal No. 50 at PCM C2 harness connector. see scheme 2 Also check if Tan and Red/Black wires at IAT sensor harness connector are shorted together. If Tan wire is shorted to ground, or shorted to Red/Black wire, repair wiring as necessary. After repairs, go to step 8. If wiring is okay, go to step 7.
6. Replace IAT sensor. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

A skewed IAT sensor may cause this DTC to set. Check IAT sensor resistance at specified temperature. See INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. If DTC P0112 cannot be duplicated, information included in failure records can be useful in determining vehicle mileage since the diagnostic test last failed. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

INTAKE AIR TEMPERATURE SENSOR RESISTANCE

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, observe IAT sensor temperature parameter. If temperature reading is less than -24°F (-31°C), go to step 4. If temperature reading is -24°F (-31°C) or more go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S25134427692001102400000).
4. Turn ignition off. Disconnect IAT sensor connector. IAT sensor is located in air intake passage of engine air induction system and has a 2-pin connector with Tan and Red/Black wires. Turn ignition on. Connect a jumper wire between Tan and Red/Black wires at IAT sensor harness connector. Using scan tool, observe IAT sensor temperature. If temperature reading is more than 266°F (130°C), go to step 6. If temperature reading is 266°F (130°C) or less, disconnect jumper wire and go to next step.
5. Connect a jumper wire between ground and Tan wire at IAT sensor harness connector. Using scan tool, observe IAT sensor temperature. If temperature reading is more than 266°F (130°C), go to step 7. If temperature reading is 266°F (130°C) or less, disconnect jumper wire and go to step 8.
6. Check for poor connections at IAT sensor connector. Repair connector as necessary. After repairs, go to step 12. If connector is okay, go to step 10.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Red/Black wire between IAT sensor harness connector and terminal No. 17 at PCM C1 harness connector. see scheme 2 If continuity exists, go to step 9. If continuity does not exist, repair open in Red/Black wire. After repairs, go to step 12.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Check for an open or short to voltage in Tan wire between IAT sensor harness connector and terminal No. 50 at PCM C2 harness connector. see scheme 2 If Tan wire is open or shorted to voltage, repair wiring as necessary. After repairs, go to step 12. If Tan wire is not open or shorted to voltage, go to next step.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor IAT sensor signal and ground circuit connections at PCM and IAT sensor connectors. Repair connectors as necessary. After repairs, go to step 12. If connectors are okay, go to step 11.
10. Replace IAT sensor. After repairs, go to step 12.
11. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
12. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
13. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

A skewed IAT sensor may cause this DTC to set. Check IAT sensor resistance at specified temperature. See INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. If DTC P0113 cannot be duplicated, information included in failure records can be useful in determining vehicle mileage since the diagnostic test last failed. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, observe ECT sensor temperature. If temperature reading is more than 266°F (130°C), go to step 4. If temperature reading is 266°F (130°C) or less, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S39052279412001102400000).
4. Turn ignition off. Disconnect ECT sensor harness connector. (Scheme 24) Turn ignition on. Using scan tool, observe ECT sensor temperature. If ECT sensor temperature reading is about -24°F (-31°C), go to step 6. If ECT sensor temperature reading is not about -24°F (-31°C), go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for a short to ground in ECT sensor signal circuit (Yellow wire) between ECT sensor harness connector and terminal No. 26 at PCM C2 harness connector. see scheme 2 Also check ECT sensor signal circuit (Yellow wire) is shorted to ECT sensor low reference circuit (Black wire) at ECT sensor harness connector. If Yellow wire is shorted to ground or shorted to Black wire, repair wiring as necessary. After repairs, go to step 8. If wiring is okay, go to step 7.
6. Replace ECT sensor. After repairs, go to step 8.
7. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Scheme 24

A skewed ECT sensor may cause this DTC to set. Check ECT sensor resistance at specified temperature. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE table. If DTC P0117 cannot be duplicated, information included in failure records can be useful in determining vehicle mileage since the diagnostic test last failed. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, observe ECT sensor temperature. If temperature reading is less than -24°F (-31°C), go to step 4. If temperature reading is -24°F (-31°C) or more, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S04340534932001102400000).
4. Turn ignition off. Disconnect ECT sensor connector. (Scheme 24) Turn ignition on. Connect a 3-amp jumper wire between Black and Yellow wires at ECT sensor harness connector. Using scan tool, observe ECT sensor temperature. If temperature reading is more than 266°F (130°C), go to step 8. If temperature reading is 266°F (130°C) or less, disconnect jumper wire and go to next step.
5. Turn ignition off. Connect a 3-amp jumper wire between ground and Yellow wire at ECT sensor harness connector. Turn ignition on. Using scan tool, observe ECT sensor temperature. If temperature reading is more than 266°F (130°C), go to step 7. If temperature reading is 266°F (130°C) or less, go to next step.
6. Turn ignition off. Disconnect jumper wire. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to voltage in ECT sensor signal circuit (Yellow wire) between ECT sensor harness connector and terminal No. 26 at PCM C2 harness connector. see scheme 2 If Yellow wire is open or shorted to voltage, repair wiring as necessary. After repairs, go to step 12. If wiring is okay, go to next step.
7. Check continuity of Black wire between ECT sensor harness connector and terminal No. 12 at PCM C1 harness connector. If continuity does not exist, repair open in Black wire. After repairs, go to step 12. If continuity exists, go to step 9.
8. Check for poor connections at ECT sensor connector. Repair connector as necessary. After repairs, go to step 12. If connector is okay, go to step 10.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 12. If connectors are okay, go to step 11.
10. Replace ECT sensor. After repairs, go to step 12.
11. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
12. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
13. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

A skewed ECT sensor may cause this DTC to set. Check ECT sensor resistance at specified temperature. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE table. If DTC P0118 cannot be duplicated, information included in failure records can be useful in determining vehicle mileage since the diagnostic test last failed. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

A skewed MAP sensor signal may cause PCM to incorrectly determine that the TP sensor is out of range. Check for an unusually low or high MAP sensor reading. If DTC is determined to be intermittent or TP sensor system is still suspect, go to DTC P1121: THROTTLE POSITION SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE and/or INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, observe TP sensor voltage parameter. If voltage is less than.16 volt, go to step 4. If voltage is.16 or more, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, go to «DTC P1122: THROTTLE POSITION SENSOR CIRCUIT INTERMITTENT LOW VOLTAGE»(ref-126121-S05843873612001102400000).
4. Turn ignition off. Disconnect TP sensor connector. Connect a 3-amp fused jumper wire between terminal "A" (Gray wire) and terminal "C" (Dark Blue wire) at TP sensor harness connector. see scheme 9 Turn ignition on. Using scan tool, observe TP sensor voltage. If voltage is 5 volts, go to step 11. If voltage is not 5 volts, go to next step.
5. Remove jumper wire. Measure voltage between terminal "A" (Gray wire) and terminal "B" (Black wire) at TP sensor harness connector. If voltage is about 5 volts, go to step 9. If voltage is not about 5 volts, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Gray wire between terminal "A" at TP sensor harness connector and terminal No. 33 at PCM C2 harness connector. see scheme 2and see scheme 9. If continuity exists, go to next step. If continuity does not exist, repair open in Gray wire. After repairs, go to step 14.
7. Using a test light connected to positive battery voltage, probe terminal "A" (Gray wire) at TP sensor harness connector. If test light does not illuminate, go to next step. If test light illuminates, repair short to ground in Gray wire between TP sensor and PCM. After repairs, go to step 14.
8. Reconnect PCM connectors. Connect DVOM between terminal "A" (Gray wire) and terminal "B" (Black wire) at TP sensor harness connector. Turn ignition on. Observe voltage reading while disconnecting all sensors, one at a time, that use a 5-volt reference signal. See WIRING DIAGRAMS article. If voltage reading changes, replace sensor that caused voltage to change. After repairs, go to step 14. If voltage does not change, reconnect connectors and go to step 10.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Dark Blue wire between terminal "C" at TP sensor harness connector and terminal No. 66 at PCM C2 harness connector. see scheme 2and see scheme 9. If continuity exists, go to next step. If continuity does not exist, repair open in Dark Blue wire. After repairs, go to step 14.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
11. Check for poor connections at TP sensor connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to next step.
12. Replace TP sensor. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, observe TP sensor voltage parameter with throttle closed. If voltage is more than 4.9 volts, go to step 4. If voltage is 4.9 volts or less, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, go to «DTC P1121: THROTTLE POSITION SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE»(ref-126121-S21728823122001102400000).
4. Turn ignition off. Disconnect TP sensor. Turn ignition on. Using scan tool, observe TP sensor voltage parameter. If voltage is zero volts, go to next step. If voltage is not zero volts, go to step 8.
5. Measure voltage between ground and terminal "A" (Gray wire) at TP sensor harness connector. see scheme 9 If voltage is 5 volts, go to next step. If voltage is not 5 volts, go to step 9.
6. Using a test light connected to positive battery voltage, probe terminal "B" (Black wire) at TP sensor harness connector. If test light illuminates, go to step 10. If test light does not illuminate, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black wire between terminal "B" at TP sensor harness connector and terminal No. 61 at PCM C1 harness connector. see scheme 2and see scheme 9. If continuity exists, go to step 15. If continuity does not exist, repair open in Black wire. After repairs, go to step 18.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 66 (Dark Blue wire) at PCM C2 harness connector. see scheme 2 If any voltage is indicated, repair short to voltage in Dark Blue wire between PCM and TP sensor. After repairs, go to step 18. If no voltage is indicated, go to step 15.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 33 (Gray wire) at PCM C2 harness connector. see scheme 2 If any voltage is indicated, repair short to voltage in Gray wire between PCM and TP sensor. After repairs, go to step 18. If no voltage is indicated, go to next step.
10. Turn ignition off. Reconnect PCM connectors. Turn ignition on. Connect a DVOM between terminal "A" (Gray wire) and terminal "B" (Black wire) at TP sensor harness connector. Note voltage reading. Using scan tool, command EGR valve to 100 percent while observing DVOM. If voltage changed, go to next step. If voltage did not change, go to step 14.
11. Disconnect EGR valve connector. see scheme 6 With DVOM still connected, command EGR valve to 100 percent. If voltage changed, go to step 13. If voltage did not change, go to next step.
12. Replace EGR valve. After repairs, go to step 18.
13. Gray wire between EGR valve and PCM is shorted to 5-volt reference circuit. Repair wiring as necessary. See WIRING DIAGRAMS article. After repairs, go to step 18.
14. Check for poor connections at TP sensor connector. Repair connector as necessary. After repairs, go to step 18. If connector is okay, go to step 16.
15. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 18. If connectors are okay, go to step 17.
16. Replace TP sensor. After repairs, go to step 18.
17. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
18. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Check coolant level. If coolant level is okay, go to next step. If coolant level is low, check cooling system for leaks. Repair as necessary and top off coolant level.
3. Turn ignition off. Disconnect ECT sensor connector. (Scheme 24) Connect a 3-amp fused jumper wire between Yellow and Black wires at ECT sensor harness connector. Turn ignition on. Using scan tool, observe ECT sensor temperature. If temperature reading is more than 280°F (138°C), go to step 7. If temperature reading is 280°F (138°C) or less, go to next step.
4. Turn ignition off. Disconnect jumper wire. Reconnect jumper wire between ground and Yellow wire at ECT sensor harness connector. Turn ignition on. Using scan tool, observe ECT sensor temperature. If temperature reading is more than 280°F (138°C), go to next step. If temperature reading is 280°F (138°C) or less, go to step 6.
5. Repair open or high resistance in Black wire between ECT sensor and PCM. After repairs, go to step 10.
6. Repair open or high resistance in Yellow wire between ECT sensor and PCM. After repairs, go to step 10.
7. Remove ECT sensor. Suspend ECT sensor and a thermometer in a pan of water. Place pan on a burner or hot plate. Measure resistance between ECT sensor terminals with sensor at specified temperature. See «ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE»(ref-126121-S13343785632001102900000) table. If resistance is as specified, go to next step. If resistance is not as specified, go to step 9.
8. Reinstall ECT sensor. Diagnose cooling system thermostat. Replace thermostat as necessary.
9. Replace ECT sensor. After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

DTC P0125 is designed to detect a skewed ECT sensor or a faulty thermostat. A skewed IAT sensor may also cause this DTC to set. IAT sensor should read near ambient temperature while driving. See INTAKE AIR TEMPERATURE SENSOR RESISTANCE table.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. NOTE: If any other DTCs are set except HO2S DTCs, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).
2. Using scan tool, clear DTCs. Reset fuel trim values. Start engine. Ensure engine is at normal operating temperature. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If scan tool indicates voltage fixed within 300-600 millivolts, go to step 4. If scan tool indicates voltage is not fixed within 300-600 millivolts, go to next step.
3. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: HO2S bank 1 sensor 1 connector water intrusion. An intermittently open HO2S bank 1 sensor 1 high signal circuit (Purple wire). An intermittently open HO2S bank 1 sensor 1 low reference circuit (Black wire). A HO2S bank 1 sensor 1 low reference circuit (Black wire) with high resistance to ground. PCM ground circuits with high resistance to ground. An inoperative HO2S bank 1 sensor 1 heater. Poor HO2S or PCM connector terminal contact. An exhaust system leak, typically within 12" upstream of HO2S bank 1 sensor 1. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 17. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S25817198862001102900000).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) Connect another jumper wire between ground and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 harness connector. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is less than 20 millivolts, go to step 7. If voltage is 20 millivolts or more, go to next step.
5. Turn ignition off. Disconnect jumper wires. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Purple wire between terminal No. 10 at PCM C2 harness connector and terminal "B" at HO2S bank 1 sensor 1 harness connector. see scheme 2and (Scheme 21). Also check continuity of Black wire between terminal "A" at HO2S bank 1 sensor 1 harness connector and terminal No. 28 at PCM C1 harness connector. If all resistance readings are less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, go to step 9.
6. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 17. If connectors are okay, go to next step.
7. Disconnect jumper wires. Connect a test light between terminal "C" (Black/White wire) and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. Start engine and observe test light. If test light illuminates, go to next step. If test light does not illuminate, go to step 10.
8. Turn ignition off. Reconnect HO2S bank 1 sensor 1 connector. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 12. If resistance is 500 ohms or more, go to step 11.
9. Repair open in Black or Purple wire between HO2S bank 1 sensor 1 and PCM. After repairs, go to step 17.
10. Repair open or high resistance in Pink/White wire between HO2S bank 1 sensor 1 and fuse No. 20 (OXY SEN fuse) in underhood fuse block, or repair open in Black/White wire between HO2S bank 1 sensor 1 and terminal No. 37 at PCM C2 harness connector. Also check fuse No. 20 (OXY SEN fuse) in underhood fuse block. After repairs, go to step 17.
11. Repair high resistance between HO2S bank 1 sensor 1 low reference circuit (Black wire) and PCM ground circuit (Black/White wire). Possible causes include the following: Poor HO2S bank 1 sensor 1 connector terminal contact. Faulty HO2S bank 1 sensor 1. Poor PCM ground connection. High PCM ground circuit resistance. Ungrounded exhaust system. Repair as necessary. After repairs, go to step 17.
12. Check for exhaust leaks upstream of HO2S bank 1 sensor 1. Leak may be very small and within 12" of HO2S bank 1 sensor 1. Repair exhaust system as necessary. After repairs, go to step 17. If exhaust system is okay, go to next step.
13. Allow engine to cool to ambient temperature. Recheck continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 15. If resistance is 500 ohms or more, go to next step.
14. Remove HO2S bank 1 sensor 1. Clean HO2S bank 1 sensor 1 threads. Apply anti-seize to HO2S bank 1 sensor 1 threads and reinstall sensor. Tighten sensor to 30 ft. lbs. (41 N.m). Recheck continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 17. If resistance is 500 ohms or more, go to next step.
15. Replace HO2S bank 1 sensor 1. After repairs, go to step 17.
16. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
17. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
18. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Check for a malfunctioning HO2S heater or heater circuit. With ignition on, HO2S voltage displayed on scan tool should gradually decrease to less than 250 millivolts or increase to more than 600 millivolts. If this does not occur, disconnect HO2S and connect a test light between HO2S ignition 1 voltage circuit (Pink/White wire) and heater low control circuit (Black/White wire). If test light does not illuminate, repair open ignition 1 voltage or sensor ground circuit as necessary. If test light illuminates and HO2S high signal circuit (Purple wire) and HO2S low reference circuit are okay, replace HO2S. Review failure records vehicle mileage since the diagnostic test last failed to determine how often condition occurs that caused DTC to set. This may assist in diagnosing condition.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed code enable criteria. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is less than 86 millivolts, go to step 4. If voltage is 86 millivolts or more, go to next step.
3. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: HO2S bank 1 sensor 1 signal circuit (Purple wire) is intermittently shorted to engine ground or low reference circuit (Black wire). HO2S bank 1 sensor 1 connector water intrusion. An exhaust leak between engine and HO2S bank 1 sensor 1. An intermittent open HO2S bank 1 sensor 1 low reference circuit (Black wire). An intermittent lean condition caused by a vacuum leak, incorrect PCV valve or defective PCV system, incorrect fuel pressure, lean fuel injectors or inaccurate Mass Airflow (MAF) sensor. A lean engine condition during power enrichment operation. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 10. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S28713892062001102400000).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is 351-551 millivolts, go to next step. If voltage is not 351-551 millivolts, go to step 6.
5. The HO2S may be detecting a lean exhaust condition. Check for one of the following conditions: HO2S bank 1 sensor 1 connector water intrusion. An exhaust leak between HO2S bank 1 sensor 1 and engine. Vacuum leaks. An incorrect or defective PCV valve or system. Incorrect fuel pressure. Lean fuel injector. An inaccurate MAF sensor. If any problems are found, repair as necessary. After repairs, go to step 10. If no problems are found, go to step 8.
6. Turn ignition off. Disconnect jumper wire. Measure resistance between ground and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 harness connector. Also measure resistance between terminal "A" (Black wire) and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 harness connector. If both resistance reading are 5 ohms or more, go to step 9. If any resistance reading is less than 5 ohms, go to next step.
7. Purple wire is shorted to ground or shorted to Black wire between HO2S bank 1 sensor 1 and PCM. Repair wiring as necessary. After repairs, go to step 10.
8. Replace HO2S bank 1 sensor 1. After repairs, go to step 10.
9. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too low will cause a lean condition. The PCM will compensate for some decrease in fuel pressure, but if fuel pressure is too low, DTC P0131 may set. Check fuel injectors. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If fuel injectors deliver improper fuel volume, DTC P0131 may set. Check for exhaust leaks. Exhaust leaks may cause outside air to be drawn into the exhaust gas stream, and pass the HO2S. This causes HO2S signal to indicate a false lean condition. Check for Secondary Air Injection (AIR) system leaks. Check AIR system hoses, check valves, and piping for leaks. Check for poor connections or for signs of any damage. Check for disconnected or damaged vacuum hoses. Check for vacuum leaks at throttle body, EGR valve, EVAP purge solenoid, and intake manifold. Check for fuel contamination. Water, even in small amounts, can be delivered to fuel injectors. Water can cause a lean exhaust. Also, excessive alcohol in the fuel can cause a lean condition. Check with customer in order to verify conditions under which the DTC set. Check if vehicle ran out of fuel. If none of the previous conditions are set, replace HO2S.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed code enable criteria. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is more than 976 millivolts, go to step 4. If voltage is 976 millivolts or less, go to next step.
3. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: HO2S bank 1 sensor 1 signal circuit (Purple wire) intermittently shorted to voltage. HO2S connector water intrusion. Silicone contamination of HO2S. An intermittently rich engine condition caused by Evaporative Emissions (EVAP) canister purge system malfunction, fuel contamination of engine oil, incorrect fuel pressure, leaking fuel pressure regulator, rich fuel injectors or inaccurate Mass Airflow (MAF) sensor. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 10. If no problems were found, see «DIAGNOSTIC AIDS»(ref-126121-S22227425552001102400000).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is 351-551 millivolts, go to next step. If voltage is not 351-551 millivolts, go to step 6.
5. The HO2S may be detecting a rich exhaust condition. Check for one of the following conditions: HO2S bank 1 sensor 1 connector water intrusion. An exhaust leak between HO2S bank 1 sensor 1 and engine. Silicone contamination of HO2S bank 1 sensor 1. Fuel contamination in engine oil. EVAP canister purge system malfunction. Incorrect fuel pressure. Leaking fuel pressure regulator. Rich fuel injectors. An inaccurate MAF sensor. If any problems are found, repair as necessary. After repairs, go to step 10. If no problems are found, go to next step.
6. Turn ignition off. Disconnect jumper wire. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 10 (Purple wire) at PCM C2 harness connector. see scheme 2 If voltage is more than 20 millivolts, go to next step. If voltage is 20 millivolts or less, go to step 9.
7. Repair short to voltage in Purple wire between HO2S bank 1 sensor 1 and PCM. After repairs, go to step 10.
8. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 1. After repairs, go to step 10.
9. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too high will cause a rich condition. The PCM will compensate for some increase in fuel pressure, but if fuel pressure is high enough, DTC P0132 may set. Check fuel injectors. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If fuel injectors deliver improper fuel volume, DTC P0132 may set. An intermittent TP sensor output will cause system to go rich due to a false indication of the engine accelerating. Throttle angle displayed on scan tool should increase steadily from 0-100 percent when opening the throttle. If this does not occur, check the TP sensor for loose mounting screws. If TP mounting screws are tight, replace the TP sensor. Check EVAP canister and hoses for fuel saturation. Check for silicone contamination. Silicone contamination of HO2S can also cause a high HO2S voltage signal. This condition is indicated by a powdery White deposit on tip of HO2S that is exposed to exhaust stream. If none of the previous conditions are present, replace HO2S.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0140 is also set, go to step 4. If DTC P0140 is not also set, go to next step.
3. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000). If no other DTCs are set, go to step 5.
4. HO2S bank 1 sensor 1 is contaminated. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 1. After repairs, go to step 18.
5. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. Start engine. Ensure engine is at normal operating temperature. If DTC resets, go to step 7. If DTC does not reset, go to next step.
6. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: Exhaust leak between engine and HO2S bank 1 sensor 1. Poor HO2S bank 1 sensor 1 connector terminal contact. Faulty HO2S bank 1 sensor 1 heater. HO2S connector water intrusion. Improperly torqued HO2S bank 1 sensor 1. Sensor should be tightened to 30 ft. lbs. (41 Nm). Poor PCM connector terminal contact. An intermittent open or short in HO2S bank 1 sensor 1 high signal circuit (Purple wire) orHO2S bank 1 sensor 1 reference low circuit (Black wire). Contaminated HO2S bank 1 sensor 1. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 18. If no problems were found, see «DIAGNOSTIC AIDS»(ref-126121-S07809124392001102400000).
7. Check for exhaust leaks between engine and HO2S bank 1 sensor 1. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Repair exhaust leaks as necessary. Check for poor connections at HO2S bank 1 sensor 1 connector and PCM connectors. PCM is located in engine compartment, inside air filter housing. If any problems are found, repair connectors as necessary. After repairs, go to step 18. If connectors are okay, go to next step.
8. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is 351-551 millivolts, go to next step. If voltage is not 351-551 millivolts, go to step 13.
9. Connect another jumper wire between ground and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 harness connector. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is less than 20 millivolts, go to next step. If voltage is 20 millivolts or more, go to step 14.
10. Disconnect jumper wire from terminal "A" (Black wire) at HO2S bank 1 sensor 1 harness connector. Ensure ignition is on. Connect a test light between ground and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 15.
11. Disconnect jumper wires. Connect a test light between terminal "C" (Black/White wire) and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. Start engine and observe test light. If test light illuminates, go to next step. If test light does not illuminate, go to step 16.
12. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. After repairs, go to step 17.
13. Turn ignition off. Check HO2S bank 1 sensor 1 high signal circuit (Purple wire) as follows: Check for a short to ground in Purple wire between terminal "B" at HO2S bank 1 sensor 1 and terminal No. 10 at PCM C2 harness connector. see scheme 2and (Scheme 21). Check if terminal "A" (Black wire) and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 are shorted together. Check if terminal "B" (Purple wire) and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 are shorted together. Repair wiring as necessary. After repairs, go to step 18.
14. Check for an open or high resistance in Purple wire between terminal "B" at HO2S bank 1 sensor 1 and terminal No. 10 at PCM C2 harness connector. see scheme 2and (Scheme 21). Also check for an open or high resistance in Black wire between terminal "A" at HO2S bank 1 sensor 1 and terminal No. 28 at PCM C1 harness connector. Repair wiring as necessary. After repairs, go to step 18.
15. Repair open or high resistance in Pink/White wire between terminal "D" at HO2S bank 1 sensor 1 and fuse No. 20 (OXY SEN fuse) in underhood fuse block. Also check fuse No. 20 (OXY SEN fuse) in underhood fuse block. After repairs, go to step 18.
16. Repair open or high resistance in Black/White wire between terminal "C" at HO2S bank 1 sensor 1 and terminal No. 37 at PCM C2 harness connector. see scheme 2and (Scheme 21). After repairs, go to step 18.
17. Replace HO2S bank 1 sensor 1. After repairs, go to next step.
18. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and for poor terminal-to-wire connections. Inspect wiring harness for damage. If harness appears to be okay, observe scan tool while moving connectors and wiring harnesses related to HO2S bank 1 sensor 1. A change in scan tool display will indicate malfunction location. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since diagnostic test last failed may help to diagnose the condition. The information may help determine how often condition that set the DTC occurs.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. NOTE: If any other DTCs are set except HO2S DTCs, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).
2. Using scan tool, clear DTCs. Reset fuel trim values. Start engine. Ensure engine is at normal operating temperature. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If scan tool indicates voltage fixed within 351-551 millivolts, go to step 4. If scan tool indicates voltage is not fixed within 351-551 millivolts, go to next step.
3. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: HO2S bank 1 sensor 1 connector water intrusion. An intermittently open HO2S bank 1 sensor 1 high signal circuit (Purple wire). An intermittently open HO2S bank 1 sensor 1 low reference circuit (Black wire). A HO2S bank 1 sensor 1 low reference circuit (Black wire) with high resistance to ground. PCM ground circuits with high resistance to ground. An inoperative HO2S bank 1 sensor 1 heater. Poor HO2S or PCM connector terminal contact. An exhaust system leak, typically within 12" upstream of HO2S bank 1 sensor 1. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 17. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S21665246692001102400000).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) Connect another jumper wire between ground and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 harness connector. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is less than 20 millivolts, go to step 7. If voltage is 20 millivolts or more, go to next step.
5. Turn ignition off. Disconnect jumper wires. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Purple wire between terminal No. 10 at PCM C2 harness connector and terminal "B" at HO2S bank 1 sensor 1 harness connector. see scheme 2and (Scheme 21). Also check continuity of Black wire between terminal "A" at HO2S bank 1 sensor 1 harness connector and terminal No. 28 at PCM C1 harness connector. If all resistance readings are less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, go to step 9.
6. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 17. If connectors are okay, go to next step.
7. Disconnect jumper wires. Connect a test light between terminal "C" (Black/White wire) and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. Start engine and observe test light. If test light illuminates, go to next step. If test light does not illuminate, go to step 10.
8. Turn ignition off. Reconnect HO2S bank 1 sensor 1 connector. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity between terminals No. 28 (Black wire) and No. 16 (Black/White wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 12. If resistance is 500 ohms or more, go to step 11.
9. Repair open in Black or Purple wire between HO2S bank 1 sensor 1 and PCM. After repairs, go to step 17.
10. Repair open or high resistance in Pink/White wire between HO2S bank 1 sensor 1 and fuse No. 20 (OXY SEN fuse) in underhood fuse block, or repair open in Black/White wire between HO2S bank 1 sensor 1 and terminal No. 37 at PCM C2 harness connector. Also check fuse No. 20 (OXY SEN fuse) in underhood fuse block. After repairs, go to step 17.
11. Repair high resistance between HO2S bank 1 sensor 1 low reference circuit (Black wire) and PCM ground circuit (Black/White wire). Possible causes include the following: Poor HO2S bank 1 sensor 1 connector terminal contact. Faulty HO2S bank 1 sensor 1. Poor PCM ground connection. High PCM ground circuit resistance. Ungrounded exhaust system. Repair as necessary. After repairs, go to step 17.
12. Check for exhaust leaks upstream of HO2S bank 1 sensor 1. Leak may be very small and within 12" of HO2S bank 1 sensor 1. Repair exhaust system as necessary. After repairs, go to step 17. If exhaust system is okay, go to next step.
13. Allow engine to cool to ambient temperature. Recheck continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 15. If resistance is 500 ohms or more, go to next step.
14. Remove HO2S bank 1 sensor 1. Clean HO2S bank 1 sensor 1 threads. Apply anti-seize to HO2S bank 1 sensor 1 threads and reinstall sensor. Tighten sensor to 30 ft. lbs. (41 Nm). Recheck continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 17. If resistance is 500 ohms or more, go to next step.
15. Replace HO2S bank 1 sensor 1. After repairs, go to step 17.
16. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
17. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
18. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Check for a malfunctioning HO2S heater or heater circuit. With ignition on, HO2S voltage displayed on scan tool should gradually decrease to less than 250 millivolts or increase to more than 600 millivolts. If this does not occur, disconnect HO2S and connect a test light between HO2S ignition 1 voltage circuit (Pink/White wire) and heater low control circuit (Black/White wire). If test light does not illuminate, repair open ignition 1 voltage or sensor ground circuit as necessary. If test light illuminates and HO2S high signal circuit (Purple wire) and HO2S low reference circuit are okay, replace HO2S. Review failure records vehicle mileage since the diagnostic test last failed to determine how often condition occurs that caused DTC to set. This may assist in diagnosing condition.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine and allow idle to stabilize for about one minute. Ensure engine is at normal operating temperature. Using scan tool, monitor HO2S heater current. If current is.45-.65 amp, see «DIAGNOSTIC AIDS»(ref-126121-S38550915352001102400000). If current is not.45-.65 amp, go to next step.
3. Turn ignition off. Remove and inspect fuse No. 20 (OXY SEN fuse) from underhood fuse block. If fuse is blown, go to step 13. If fuse is okay, reinstall fuse and go to next step.
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Turn ignition on. Using a test light connected to ground, probe terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) If test light illuminates, go to next step. If test light does not illuminate, go to step 8.
5. Connect a test light between terminal "C" (Black/White wire) and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. Start engine. If test light illuminates, leave test light connected, turn ignition off and go to next step. If test light does not illuminate, go to step 7.
6. Turn ignition on. If test light illuminates, go to step 10. If test light does not illuminate, go to step 11.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Measure resistance of Black/White wire between terminal No. 37 at PCM C2 harness connector and terminal "C" at HO2S bank 1 sensor 1 harness connector. see scheme 2and (Scheme 21). If resistance is less than 5 ohms, go to step 14. If resistance is 5 ohms or more, go to step 9.
8. Repair open in Pink/White wire between terminal "D" at HO2S bank 1 sensor 1 and fuse No. 20 (OXY SEN fuse) in underhood fuse block. Also check fuse No. 20 (OXY SEN fuse) in underhood fuse block. After repairs, go to step 16.
9. Repair open in Black/White wire between terminal "C" at HO2S bank 1 sensor 1 and terminal No. 37 at PCM C2 harness connector. After repairs, go to step 16.
10. Check for short to ground in Black/White wire between terminal "C" at HO2S bank 1 sensor 1 and terminal No. 37 at PCM C2 harness connector. Repair wiring as necessary. After repairs, go to step 16. If Black/White wire is okay, go to step 14.
11. Check for poor connections at HO2S bank 1 sensor 1 connector. Repair connector as necessary. After repairs, go to step 16. If connector is okay, go to next step.
12. Replace HO2S bank 1 sensor 1. After repairs, go to step 16.
13. Repair short to ground in Pink/White wire between fuse No. 20 (OXY SEN fuse) in underhood fuse block and HO2S bank 1 sensor 1. After repairs, go to step 16.
14. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 16. If connectors are okay, go to next step.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Review failure records vehicle mileage since the diagnostic test last failed to determine how often condition occurs that caused DTC to set. This may assist in diagnosing condition. If problem is intermittent, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed in code enable criteria. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is less than 86 millivolts, go to step 4. If voltage is 86 millivolts or more, go to next step.
3. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: HO2S bank 1 sensor 2 signal circuit (Purple wire) is intermittently shorted to engine ground or low reference circuit (Black wire). HO2S bank 1 sensor 2 connector water intrusion. An exhaust leak between engine and HO2S bank 1 sensor 2. An intermittent lean condition caused by a vacuum leak, incorrect PCV valve or defective PCV system, incorrect fuel pressure, lean fuel injectors or inaccurate Mass Airflow (MAF) sensor. A lean engine condition during power enrichment operation. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 10. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S17746621232001102400000).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 2connector. HO2S bank 1 sensor 2 is located behind catalytic converter. Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 21) Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is 351-551 millivolts, go to next step. If voltage is not 351-551 millivolts, go to step 6.
5. The HO2S may be detecting a lean exhaust condition. Check for one of the following conditions: HO2S bank 1 sensor 2 connector water intrusion. An exhaust leak between HO2S bank 1 sensor 2 and engine. Vacuum leaks. An incorrect or defective PCV valve or system. Incorrect fuel pressure. Lean fuel injector. An inaccurate MAF sensor. If any problems are found, repair as necessary. After repairs, go to step 10. If no problems are found, go to step 8.
6. Turn ignition off. Disconnect jumper wire. Measure resistance between ground and terminal "B" (Purple wire) at HO2S bank 1 sensor 2 harness connector. Also measure resistance between terminal "A" (Black wire) and terminal "B" (Purple wire) at HO2S bank 1 sensor 2 harness connector. If both resistance reading are 5 ohms or more, go to step 9. If any resistance reading is less than 5 ohms, go to next step.
7. Purple wire is shorted to ground or shorted to Black wire between HO2S bank 1 sensor 2 and PCM. Repair wiring as necessary. After repairs, go to step 10.
8. Replace HO2S bank 1 sensor 2. After repairs, go to step 10.
9. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check for faulty PCM to engine grounds. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too low will cause a lean condition. Performing fuel injector coil test may help isolate an intermittent condition. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Check exhaust system for leaks. Exhaust leaks may cause outside air to be drawn into the exhaust gas stream, and pass the HO2S. This causes the HO2S signal to indicate a false lean condition. Check for fuel contamination. Water, even in small amounts, can be delivered to fuel injectors. Water can cause a lean exhaust. Also, excessive alcohol in the fuel can cause a lean condition. For intermittent conditions, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Reviewing failure records vehicle mileage since diagnostic test last failed may assist in diagnosing condition. Information may help determine how often condition that set DTC occurs.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions listed code enable criteria. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is more than 976 millivolts, go to step 4. If voltage is 976 millivolts or less, go to next step.
3. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: HO2S bank 1 sensor 2 signal circuit (Purple wire) intermittently shorted to voltage. HO2S connector water intrusion. Silicone contamination of HO2S. An intermittently rich engine condition caused by Evaporative Emissions (EVAP) canister purge system malfunction, fuel contamination of engine oil, incorrect fuel pressure, leaking fuel pressure regulator, rich fuel injectors or inaccurate Mass Airflow (MAF) sensor. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 10. If no problems were found, see «DIAGNOSTIC AIDS»(ref-126121-S30789253662001102400000).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 2 connector. HO2S bank 1 sensor 2 is located behind catalytic converter. Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 21) Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is 351-551 millivolts, go to next step. If voltage is not 351-551 millivolts, go to step 6.
5. The HO2S may be detecting a rich exhaust condition. Check for one of the following conditions: HO2S bank 1 sensor 2 connector water intrusion. An exhaust leak between HO2S bank 1 sensor 2 and engine. Silicone contamination of HO2S bank 1 sensor 2. Fuel contamination in engine oil. EVAP canister purge system malfunction. Incorrect fuel pressure. Leaking fuel pressure regulator. Rich fuel injectors. An inaccurate MAF sensor. If any problems are found, repair as necessary. After repairs, go to step 10. If no problems are found, go to next step.
6. Turn ignition off. Disconnect jumper wire. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 11 (Purple wire) at PCM C2 harness connector. see scheme 2 If voltage is more than 20 millivolts, go to next step. If voltage is 20 millivolts or less, go to step 9.
7. Repair short to voltage in Purple wire between HO2S bank 1 sensor 2 and PCM. After repairs, go to step 10.
8. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 2. After repairs, go to step 10.
9. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Check HO2S wire routing. HO2S wiring may be routed incorrectly and contacting exhaust system. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too high will cause a rich condition. The PCM will compensate for some increase in fuel pressure, but if fuel pressure is high enough, DTC P0138 may set. Check fuel injectors. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If fuel injectors deliver improper fuel volume, DTC P0138 may set. An intermittent TP sensor output will cause system to go rich due to a false indication of the engine accelerating. Throttle angle displayed on scan tool should increase steadily from 0-100 percent when opening the throttle. If this does not occur, check the TP sensor for loose mounting screws. If TP mounting screws are tight, replace the TP sensor. Check EVAP canister and hoses for fuel saturation. Check for silicone contamination. Silicone contamination of HO2S can also cause a high HO2S voltage signal. This condition is indicated by a powdery White deposit on tip of HO2S that is exposed to exhaust stream. If none of the previous conditions are present, replace HO2S.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. NOTE: If any other DTCs are set except HO2S DTCs, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).
2. Using scan tool, clear DTCs. Reset fuel trim values. Start engine. Ensure engine is at normal operating temperature. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If scan tool indicates voltage is fixed within 351-551 millivolts, go to step 4. If scan tool indicates voltage is not fixed within 351-551 millivolts, go to next step.
3. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: HO2S bank 1 sensor 2 connector water intrusion. An intermittently open HO2S bank 1 sensor 2 high signal circuit (Purple wire). An intermittently open HO2S bank 1 sensor 2 low reference circuit (Black wire). A HO2S bank 1 sensor 2 low reference circuit (Black wire) with high resistance to ground. PCM ground circuits with high resistance to ground. An inoperative HO2S bank 1 sensor 2 heater. Poor HO2S or PCM connector terminal contact. An exhaust system leak, typically within 12" upstream of HO2S bank 1 sensor 2. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 17. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S07889514912001102400000).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 2 connector. HO2S bank 1 sensor 2 is located behind catalytic converter. Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 21) Connect another jumper wire between ground and terminal "B" (Purple wire) at HO2S bank 1 sensor 2 harness connector. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is less than 20 millivolts, go to step 7. If voltage is 20 millivolts or more, go to next step.
5. Turn ignition off. Disconnect jumper wires. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Purple wire between terminal No. 11 at PCM C2 harness connector and terminal "B" at HO2S bank 1 sensor 2 harness connector. see scheme 2and (Scheme 21). Also check continuity of Black wire between terminal "A" at HO2S bank 1 sensor 2 harness connector and terminal No. 28 at PCM C1 harness connector. If all resistance readings are less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, go to step 9.
6. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 17. If connectors are okay, go to next step.
7. Disconnect jumper wires. Connect a test light between terminal "C" (Black/White wire) and terminal "D" (Pink/Black wire) at HO2S bank 1 sensor 2 harness connector. Start engine and observe test light. If test light illuminates, go to next step. If test light does not illuminate, go to step 10.
8. Turn ignition off. Reconnect HO2S bank 1 sensor 2 connector. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 12. If resistance is 500 ohms or more, go to step 11.
9. Repair open in Black or Purple wire between HO2S bank 1 sensor 2 and PCM. After repairs, go to step 17.
10. Repair open or high resistance in Pink/Black wire between terminal "D" at HO2S bank 1 sensor 2 and fuse No. 20 (OXY SEN fuse) in underhood fuse block, or repair open in Black/White wire between terminal "C" at HO2S bank 1 sensor 2 and terminal No. 48 at PCM C2 harness connector. Also check fuse No. 20 (OXY SEN fuse) in underhood fuse block. After repairs, go to step 17.
11. Repair high resistance between HO2S bank 1 sensor 2 low reference circuit (Black wire) and PCM ground circuit (Black/White wire). Possible causes include the following: Poor HO2S bank 1 sensor 2 connector terminal contact. Faulty HO2S bank 1 sensor 2. Poor PCM ground connection. High PCM ground circuit resistance. Ungrounded exhaust system. Repair as necessary. After repairs, go to step 17.
12. Check for exhaust leaks upstream of HO2S bank 1 sensor 2. Leak may be very small and within 12" of HO2S bank 1 sensor 2. Repair exhaust system as necessary. After repairs, go to step 17. If exhaust system is okay, go to next step.
13. Allow engine to cool to ambient temperature. Recheck continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 15. If resistance is 500 ohms or more, go to next step.
14. Remove HO2S bank 1 sensor 2. Clean HO2S bank 1 sensor 2 threads. Apply anti-seize to HO2S bank 1 sensor 2 threads and reinstall sensor. Tighten sensor to 30 ft. lbs. (41 N.m). Recheck continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 17. If resistance is 500 ohms or more, go to next step.
15. Replace HO2S bank 1 sensor 2. After repairs, go to step 17.
16. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
17. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
18. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Check for a malfunctioning HO2S heater or heater circuit. With ignition on, HO2S voltage displayed on scan tool should gradually decrease to less than 250 millivolts or increase to more than 600 millivolts. If this does not occur, disconnect HO2S and connect a test light between HO2S ignition 1 voltage circuit (Pink/White wire) and heater low control circuit (Black/White wire). If test light does not illuminate, repair open ignition 1 voltage or sensor ground circuit as necessary. If test light illuminates and HO2S high signal circuit (Purple wire) and HO2S low reference circuit are okay, replace HO2S. Review failure records vehicle mileage since the diagnostic test last failed to determine how often condition occurs that caused DTC to set. This may assist in diagnosing condition.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, clear DTCs. Observe DTC information for 30 seconds. If DTC P0036 sets, go to «DTC P0036: HEATED OXYGEN SENSOR HEATER CONTROL CIRCUIT - BANK 1 SENSOR 2»(ref-126121-S17939192072001102400000). If DTC P0036 is not set, go to next step. NOTE: HO2S must cool down and ignition must be off for at least 30 minutes before continuing.
3. Turn ignition on and as quickly as possible, observe and record HO2S bank 1 sensor 2 voltage. Monitor voltage for 2 minutes and record voltage reading. If HO2S bank 1 sensor 2 reading increases or decreases from initial voltage reading by at least 150 millivolts, go to next step. If HO2S bank 1 sensor 2 reading does not increase or decrease from initial voltage reading by at least 150 millivolts, go to step 5.
4. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: An intermittent open or high resistance in HO2S bank 1 sensor 2 high signal circuit (Purple wire). An intermittent open or high resistance in HO2S bank 1 sensor 2 ignition 1 voltage circuit (Pink/Black wire). Poor HO2S or PCM connector terminal contact. Faulty HO2S bank 1 sensor 2. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 15. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S21665246692001102400000).
5. Turn ignition off. Raise and support vehicle. Remove HO2S bank 1 sensor 2 wiring harness heat shield. HO2S bank 1 sensor 2 is located behind catalytic converter. Disconnect HO2S bank 1 sensor 2. Connect a test light between terminal "C" (Black/White wire) and terminal D" (Pink/Black wire) at HO2S bank 1 sensor 2 harness connector. (Scheme 21) If test light illuminates, go to next step. If test light does not illuminate, turn ignition off and go to step 7.
6. Disconnect test light. Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 2 harness connector. Connect another jumper wire between ground and terminal "B" (Purple wire) at HO2S bank 1 sensor 2 harness connector. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 2 voltage. If voltage is less than 20 millivolts, go to step 9. If voltage is 20 millivolts or more, go to step 8.
7. Connect a test light between ground and terminal "D" (Pink/Black wire) at HO2S bank 1 sensor 2 harness connector. Turn ignition on. If test light illuminates, go to step 10. If test light does not illuminate, go to step 11.
8. Turn ignition off. Disconnect jumper wires. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Purple wire between terminal No. 11 at PCM C2 harness connector and terminal "B" at HO2S bank 1 sensor 2 harness connector. see scheme 2and (Scheme 21). Also check continuity of Black wire between terminal "A" at HO2S bank 1 sensor 2 harness connector and terminal No. 28 at PCM C1 harness connector. If all resistance readings are less than 5 ohms, go to step 13. If any resistance reading is 5 ohms or more, go to step 12.
9. Replace HO2S bank 1 sensor 2. After repairs, go to step 15.
10. Repair open in Black/White wire between terminal "C" at HO2S bank 1 sensor 2 and terminal No. 48 at PCM C2 harness connector. After repairs, go to 15.
11. Repair open or high resistance in Pink/White wire between HO2S bank 1 sensor 2 and fuse No. 20 (OXY SEN fuse) in underhood fuse block. Also check fuse No. 20 (OXY SEN fuse) in underhood fuse block. After repairs, go to step 15.
12. Repair open or high resistance in Purple wire between terminal "B" at HO2S bank 1 sensor 2 and terminal No. 11 at PCM C2 harness connector, or repair open or high resistance in Black wire between terminal "A" at HO2S bank 1 sensor 2 and terminal No. 28 at PCM C1 harness connector. After repairs, go to step 15.
13. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 15. If connectors are okay, go to next step.
14. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
15. Turn ignition on and as quickly as possible, observe and record HO2S bank 1 sensor 2 voltage. Monitor voltage for 2 minutes and record voltage reading. If HO2S bank 1 sensor 2 reading increases or decreases from initial voltage reading by at least 150 millivolts, go to next step. If HO2S bank 1 sensor 2 reading does not increase or decrease from initial voltage reading by at least 150 millivolts, go to step 2.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. Do not solder HO2S wires. Soldering wires will result in loss of air reference to sensor.

Review failure records vehicle mileage since the diagnostic test last failed to determine how often condition occurs that caused DTC to set. This may assist in diagnosing condition. For intermittent conditions, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. NOTE: If any other DTCs are set, repair DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).
2. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, record LONG TERM FUEL TRIM data. Turn ignition off. Turn ignition on. Using scan tool, review FREEZE FRAME RECORDS and/or FAILURE RECORDS and record data. If long term fuel trim is more than 23 percent, go to next step. If long term fuel trim is 23 percent or less, see «DIAGNOSTIC AIDS»(ref-126121-S28939188452001102400000).
3. Start engine and allow it to idle. Using scan tool, observe HO2S voltage. If voltage is 200-800 millivolts and fluctuating, go to next step. If voltage is not 200-800 millivolts or is not fluctuating, go to step 5.
4. Turn ignition off. Check vacuum hoses for splits, kinks and proper routing. Check for contaminated fuel. Ensure fuel tank has enough fuel. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure that is too low can cause a lean condition. If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to step 6.
5. Turn ignition off. Ensure HO2S is installed correctly and wiring harness is not touching exhaust. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for continuity between terminal "A" (Black wire) and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) If continuity exists, Black and Purple wires are shorted together. Repair wiring as necessary. After repairs, go to step 7. If continuity does not exist, diagnose fuel system. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
6. Operate engine at idle. Check for missing, loose, or leaking exhaust components. Check for vacuum leaks at intake manifold, throttle body and injector "O" rings. Check air induction system and air intake ducts for leaks. Check crankcase ventilation system for leaks. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, check engine mechanical condition and repair as necessary.
7. After repairs, using scan tool fuel trim reset function, reset long term fuel trim. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

System will go lean if an injector is not suppling enough fuel. A lean condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel. An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Do not attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. NOTE: If any other DTCs are set, repair DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .
2. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, record long term fuel trim data. Turn ignition off. Turn ignition on. Using scan tool, record LONG TERM FUEL TRIM data. Turn ignition off. Turn ignition on. Using scan tool, review FREEZE FRAME RECORDS and/or FAILURE RECORDS and record data. If long term fuel trim is less than -13 percent, go to next step. If long term fuel trim is -13 percent or more, see «DIAGNOSTIC AIDS»(ref-126121-S36451129522001102400000) .
3. Start engine and allow it to idle. Using scan tool, observe HO2S voltage. If voltage is 200-800 millivolts and fluctuating, go to next step. If voltage is not 200-800 millivolts or is not fluctuating, go to step 5 .
4. Turn ignition off. Check Mass Airflow (MAF) sensor inlet screen for blockage. Check vacuum hoses for splits, kinks and proper routing. Check for collapsed or restricted air intake duct. Check for restricted or dirty air filter. Check for throttle body blockage. If any problems are found, repair as necessary. After repairs, go to step 7 . If no problems are found, go to step 6 .
5. Turn ignition off. Ensure HO2S is installed correctly and wiring harness is not touching exhaust. If any problems are found, repair as necessary. After repairs, go to step 7 . If no problems are found, diagnose fuel system. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
6. Check for excessive fuel in crankcase. Check evaporative emissions control system. See FUEL EVAPORATION under EMISSION SYSTEMS & SUBSYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Check fuel pressure regulator for proper operation. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article. Ensure all fuel injectors are functioning properly. Perform fuel injector balance test. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, check engine mechanical condition and repair as necessary.
7. After repairs, using scan tool fuel trim reset function, reset long term fuel trim. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

Fuel contamination, such as water or alcohol will affect fuel trim. A bad MAF sensor can cause a rich condition. Using scan tool, review failure records. If an intermittent condition is suspect, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Using scan tool, record FREEZE FRAME and/or FAILURE RECORDS data for this DTC, then clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, observe misfire current counters. If any misfire current counters are incrementing, go to step 4 . If no misfire current counters are incrementing, go to next step.
3. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S39458745932001102400000) .
4. Turn ignition off. Disconnect fuel injector connector for DTC that is set. See «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(ref-126121-S10205114812001102400000) table. Turn ignition on. Using a test light connected to ground, probe ignition voltage circuit at suspect fuel injector harness connector. See «INJECTOR IGNITION VOLTAGE CIRCUIT IDENTIFICATION»(ref-126121-S26763106082001102400000) table. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 . DIAGNOSTIC TROUBLE CODE IDENTIFICATION DTC Injector No. P0201 (1) 1 P0202 2 P0203 3 P0204 4 P0205 5 P0206 6 (1) Injector No. 1 is the first injector on right (rear) cylinder head. INJECTOR IGNITION VOLTAGE CIRCUIT IDENTIFICATION Injector No. Wire Color 1 Pink/White 2 Pink/White 3 Pink/Black 4 Pink/Black 5 Pink/Black 6 Pink/Black
5. Connect Fuel Injector Test Light (J 34730-2C) between suspect fuel injector harness connector. Start engine. If test light blinks, go to step 9 . If test light does not blink, go to next step.
6. If test light remains on at all times, go to step 8 . If test light does not remain on at all times, go to next step.
7. Check suspect fuel injector control circuit for short to voltage or open. See «INJECTOR CONTROL CIRCUIT IDENTIFICATION»(ref-126121-S27021680422001102400000) table. If any problems are found, repair wiring as necessary. After repairs, go to step 14 . If no problems are found, go to step 10 .
8. Using a test light connected to positive battery voltage, probe control circuit at suspect fuel injector harness connector. See «INJECTOR CONTROL CIRCUIT IDENTIFICATION»(ref-126121-S27021680422001102400000) table. If test light illuminates, repair short to ground in fuel injector control circuit. After repairs, go to step 14 . If test light does not illuminate, go to step 13 .
9. Check suspect fuel injector connector for poor connections. Repair connector as necessary. After repairs, go to step 14 . If no problem was found, go to step 12 .
10. Check PCM connectors for poor connections. PCM is located in engine compartment, inside air filter housing. Repair connectors as necessary. After repairs, go to step 14 . If connectors are okay, go to step 13 .
11. Repair open or short to ground in ignition voltage circuit between fuel injector and underhood fuse block. After repairs, go to step 14 .
12. Replace fuel injector. See FUEL SYSTEMS in appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 14 .
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

Performing fuel injector coil test may help isolate an intermittent condition. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If an intermittent condition is suspect, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

INJECTOR CONTROL CIRCUIT IDENTIFICATION

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, command fuel pump relay on and off. Listen for fuel pump relay operating noise. Fuel pump relay is located in rear fuse block. Rear fuse block is located underneath driver's side rear seat. If fuel pump relay turns on and off as commanded, go to next step. If fuel pump relay does not turn on and off as commanded, go to step 4.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Remove fuel pump relay. Turn ignition on. Using a test light connected to ground, probe fuel pump relay control circuit (Dark Green/White wire) at fuel pump relay connector in rear fuse block. See WIRING DIAGRAMS article. Using scan tool, command fuel pump relay on and off. If test light turns on and off as commanded, disconnect test light and go to next step. If test light does not turn on and off as commanded, go to step 6.
5. Turn ignition off. Connect a test light between fuel pump relay control circuit (Dark Green/White wire) and fuel pump relay ground circuit (Black wire) at fuel pump relay connector in rear fuse block. Turn ignition on. Using scan tool, command fuel pump relay on and off. If test light turns on and off as commanded, go to step 9. If test light does not turn on and off as commanded, go to step 11.
6. If test light is always on, go to step 8. If test light is always off, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in fuel pump relay control circuit (Dark Green/White wire) between fuel pump relay connector in rear fuse block and terminal No. 3 at PCM C2 harness connector. see scheme 2 If Dark Green/White wire is open or shorted to ground, repair wiring as necessary. After repairs, go to step 14. If Dark Green/White wire is not open or shorted to ground, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to ground, probe terminal No. 3 (Dark Green/White wire) at PCM C2 harness connector. see scheme 2 If test light illuminates, repair short to voltage in Dark Green/White wire between PCM and fuel pump relay connector. If test light does not illuminate, go to step 10.
9. Check fuel pump relay connector for poor connections. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
10. Check PCM connectors for poor connections. PCM is located in engine compartment, inside air filter housing. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
11. Repair open in fuel pump relay ground circuit. See WIRING DIAGRAMS article. After repairs, go to step 14.
12. Replace fuel pump relay. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Incorrect CKP system variation data in PCM may cause DTC to set with no apparent misfire. Any of the following conditions can cause incorrect CKP system variation data: Replace engine. Replacing PCM. Reprogramming PCM. Replacing CKP sensor. Performing internal engine repairs that affect CKP sensor-to-crankshaft reluctor wheel relationship. If none of the listed conditions apply to vehicle, go to next step. If any of the listed conditions apply to vehicle, CKP system variation learn procedure must be performed before continuing with misfire diagnosis. See «CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE»(ref-126121-S09213767522001102400000) under PROGRAMMING. NOTE: If any other DTCs are set, repair DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).
3. Start engine. Using scan tool, select MISFIRE BAR GRAPH or MISFIRE COUNTERS. If any cylinders indicate excessive misfire, go to next step. If no cylinders indicate excessive misfire, see «DIAGNOSTIC AIDS»(ref-126121-S27940537692001102400000).
4. If misfire seems to be affecting specific cylinders, go to step 8. If misfire is random to all cylinders, go to next step.
5. Turn ignition off. Check PCM and ignition control module grounds. See WIRING DIAGRAMS article. Ensure engine grounds are clean, tight and in their proper locations. If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to next step.
6. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not as specified, repair fuel system as necessary. After repairs, go to step 14. If fuel pressure is as specified, go to next step.
7. Check for fuel contamination. Water, even in small amounts, can be delivered to fuel injectors. Water can cause a lean exhaust. Also, excessive alcohol in the fuel can cause a lean condition. If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go next step.
8. Operate engine at idle. Check for vacuum leaks at intake manifold, throttle body and injector "O" rings. If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to next step.
9. Remove EGR valve. see scheme 6 Check EGR valve for a partially stuck open pintle. Check EGR valve passages for restrictions or carbon deposits that may interfere with EGR pintle closing completely. If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to next step.
10. Perform fuel injector balance test and fuel injector coil test. See FUEL INJECTOR BALANCE TEST and FUEL INJECTOR COIL TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to next step.
11. Check ignition system operation. See ELECTRONIC IGNITION SYSTEM DIAGNOSIS in appropriate SYSTEM & COMPONENT TESTING article. If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to next step.
12. Check for the following mechanical conditions: Damaged accessory drive belt or pulley. Damaged driven accessory (generator, water pump, drive belt tensioner, etc.). Loose or broke motor mount. Engine mechanical problems. If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to next step.
13. Ensure transaxle torque converter clutch is functioning properly. See appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Using scan tool, perform CKP system variation learn procedure. See CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE under PROGRAMMING. Ensure all connections are clean and properly tightened. A damaged serpentine belt or belt driven accessory can cause engine load variations sufficient to set a misfire DTC. Check fuel pressure. See appropriate BASIC DIAGNOSTIC PROCEDURES article. A malfunctioning fuel pump, a plugged filter, or a malfunctioning fuel system pressure regulator will contribute to a lean condition. Performing fuel injector coil test. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Check for contaminated fuel. Excessive open loop operation caused by extended idling or short trip driving may leave deposits on heated oxygen sensors. Deposits cause oxygen sensors to respond slowly to exhaust oxygen content, affecting fuel control and causing a misfire to be indicated at idle. This condition is not permanent. In order to determine if this condition is causing DTC P0300 to be set, review FREEZE FRAME/FAILURE RECORDS for DTC P0300. If DTC P0300 occurs at high engine speeds, the condition described above did not cause DTC P0300 to set. If DTC P0300 occurs at idle or very low engine speeds and at engine coolant temperatures less than 176°F (80°C), the condition described is very likely the cause of the DTC P0300 being set. The deposits on the heated oxygen sensors can be eliminated by operating vehicle fully warm at mass airflows more than 15 grams/sec. DTC may set if vehicle misfires while running out of fuel. If no misfire is currently present, but history counters indicate random misfire was once present, ask customer if vehicle has run out of fuel. If this is the case, no further repair may be necessary.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . After repairs, go to next step.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to step 2 . If DTC runs and passes, go to next step.
5. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. NOTE: If engine is making a knock noise, repair engine mechanical condition before continuing with this test.
2. Using scan tool, observe and record the FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Set DVOM to 400 mV AC hertz scale. Check frequency between ground and terminal No. 33 at PCM C1 harness connector. see scheme 2 While observing DVOM, use a non-metallic object and tap on side of engine block near knock sensor. Knock sensor is located near engine oil pressure sensor. (Scheme 22) If frequency fluctuates while tapping block, go to step 7. If frequency does not fluctuate, go to next step.
4. Check for an open, short to ground and short to voltage in Dark Blue wire between knock sensor harness connector and terminal No. 33 at PCM C1 harness connector. If any problems are found, repair wiring as necessary. After repairs, go to step 9. If no problems are found, go to next step.
5. Check knock sensor connector for poor connection. Repair connector as necessary. After repairs, go to step 9. If connector is okay, go to next step.
6. Replace knock sensor. After repairs, go to step 9.
7. Check for poor connections at terminal No. 33 (Dark Blue wire) at PCM C1 harness connector. Repair connector as necessary. After repairs, go to step 9. If connector is okay, go to next step.
8. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
9. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
10. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

If condition is intermittent, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. Ignition system DTCs may set with ignition switch in START position if starter relay or starter is inoperative. When PCM enables starter operation, the PCM also initiates diagnostic test routines for DTCs P0335, P0340, and P0385. The PCM will not receive signal input from CKP and CMP sensors if a condition exists which prevents engine from cranking. When this occurs, DTCs will set. If DTC P0335, P0340, and/or P0385 are set and no problem is found, check if there is a no-crank condition or an intermittent no-crank condition. Check if an attempt was made to crank engine with shift lever not in Park or Neutral.

When diagnosing CKP sensor, it may be necessary to enable a specific decode mode (ANGLE, TIME A or TIME B). In order to enable a specific crank decode, use scan tool and perform the following

1. Turn ignition on.
2. Select ENGINE OUTPUT CONTROLS.
3. Select CRANK POSITION SENSING DECODE mode.
4. Select desired mode (ANGLE, TIME A or TIME B) by pressing SELECT STATE.
5. Command decode mode by pressing COMMAND STATE.

The commanded state remains valid for current ignition cycle. A specific decode mode cannot be commanded with engine running, or after commanding a desired decode mode. In order to command a different decode mode, ignition must be cycled off and on.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine. Using scan tool, monitor CMP sensor data. If scan tool indicates a CMP sensor RPM and a CAM signal are present, go to next step. If scan tool does not indicate a CMP sensor RPM and CAM signal are present, go to step 5.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to step 5. If DTC does not reset, go to next step.
4. Ensure engine is running. Observe scan tool and wiggle CMP sensor wiring harness. CMP sensor is located in front of right (rear) cylinder head. If CMP sensor status changes or RPM becomes erratic, go to step 11. If CMP sensor status does not change and RPM does not become erratic, see «DIAGNOSTIC AIDS»(ref-126121-S35029877962001110200000).
5. Turn ignition off. Disconnect CMP sensor connector. CMP sensor is located in front of right (rear) cylinder head. Turn ignition on. Measure voltage between ground and Red wire at CMP sensor harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 12.
6. Measure voltage between Red and Pink/Black wires at CMP sensor harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13.
7. Ensure ignition is on. Using a test light connected to positive battery voltage, repeatedly touch Orange wire at CMP sensor harness connector. Using scan tool, observe CMP sensor data. If scan tool indicates an RPM when touching Orange wire, go to step 17. If scan tool does not indicate an RPM when touching Orange wire, go to next step.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Measure voltage between ground and Orange wire at CMP sensor harness connector. If any voltage is indicated, go to step 16. If no voltage is indicated, go to next step.
9. Check continuity of Orange wire between CMP sensor harness connector and terminal No. 7 at PCM C1 harness connector. see scheme 2 If continuity exists, go to next step. If continuity does not exist, go to step 14.
10. Check for continuity between ground and Orange wire at CMP sensor harness connector. If continuity exists, go to step 15. If continuity does not exist, go to step 19.
11. Repair wiring harness or connectors as necessary. After repairs, go to step 21.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Red wire between CMP sensor harness connector and terminal No. 72 at PCM C2 harness connector. see scheme 2 If continuity exists, go to step 19. If continuity does not exist, repair open in Red wire. After repairs, go to step 21.
13. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Pink/Black wire between CMP sensor harness connector and terminal No. 73 at PCM C2 harness connector. see scheme 2 If continuity exists, go to step 19. If continuity does not exist, repair open in Pink/Black wire. After repairs, go to step 21.
14. Repair open in Orange wire. After repairs, go to step 21.
15. Repair short to ground in Orange wire. After repairs, go to step 21.
16. Repair short to voltage in Orange wire. After repairs, go to step 21.
17. Check for poor connections at CMP sensor connector. Repair connector as necessary. After repairs, go to step 21. If connector is okay, go to next step.
18. Replace CMP sensor. After repairs, go to step 21.
19. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 21. If connectors are okay, go to next step.
20. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
21. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
22. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Ensure engine grounds are clean and tight, including the main battery ground cable at engine block. If no problems are found with CMP sensor or related circuitry, and if DTC P0340 continues to set, engine should be checked for incorrect cam timing. CKP and CMP sensor DTCs may set if the key is turned to START position and starter is inoperative. If P0335, P0340, and P0385 are set and no problems are found, check for the following

1. Check if there is a no-crank condition or an intermittent no-crank condition.
2. Check if an attempt was made to crank engine with shift lever not in Park or Neutral.

DTC P0340 may set if engine cranking speed is less than 120 RPM. Reviewing FAILURE RECORDS may help to determine if the DTC set during cranking with an engine speed of less than 120 RPM. If this was the situation, correct cause of slow cranking speed. Scan tool parameter CMP SENSOR DATA will not display an accurate RPM value less than 120 RPM. If problem is intermittent, See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If any MAP DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000). If no MAP DTCs are set, go to next step.
3. Check exhaust system for leaks and modification of original parts. If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to next step.
4. Check EGR valve gasket and pipes for leaks. see scheme 6 If any problems are found, repair EGR system as necessary. After repairs, go to step 7. If no problems are found, go to next step.
5. Remove EGR valve. Check EGR valve pintle and passages for leaks and/or restrictions. If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to next step.
6. Remove EGR inlet and outlet pipes from intake and exhaust manifolds. Inspect manifold EGR ports, inlet pipes and outlet pipes for blockage/damage. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S21159991792001102400000).
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

If EGR valve shows signs of excessive heat, check exhaust system for blockage or for a plugged catalytic converter. A vacuum restriction to the MAP sensor can cause EGR flow test to fail due to insufficient MAP changes being monitored during the test. An engine that is running poorly may cause this DTC to set. Check for poor connection or damaged wiring harness. If wiring harness appears to be okay, observe EGR position sensor display on scan tool while moving connectors and wiring harnesses that are related to EGR valve. A change in the display indicates location of malfunction.

In order to verify a repair, select CLEAR INFO on scan tool, and run EGR flow test, keeping the following conditions in mind

1. PCM will only run EGR flow test during a gradual deceleration.
2. PCM will only run EGR test during a closed throttle condition.
3. PCM will only run EGR test with vehicle speeds at more than 23 MPH.
4. Several deceleration cycles will be necessary in order to run a sufficient number of EGR flow test samples. A sufficient number of samples is usually 5-15 samples.
5. If within enabling RPM (900-1200 RPM) engine speed decreases more than 500 RPM, PCM will reset test.
6. If within enabling RPM (900-1200 RPM) engine speed increases more than 75 RPM, PCM will reset test.
7. When PCM commands EGR valve open, engine speed will decrease. If engine speed decreases to less than 500 RPM, test will not run.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. NOTE: If DTC P0403 or P0405 is set, diagnose affected DTC(s) first. See «DTC P0403: EXHAUST GAS RECIRCULATION SOLENOID CONTROL CIRCUIT»(ref-126121-S04118872412001102400000) or «DTC P0405: EXHAUST GAS RECIRCULATION POSITION SENSOR CIRCUIT LOW VOLTAGE»(ref-126121-S18156668082001102400000).
2. Ensure ignition is on. Using scan tool, command EGR valve from zero to 100 percent. If EGR position sensor remains within 20 percent of desired EGR position at all commanded positions, go to next step. If EGR position sensor does not remain within 20 percent of desired EGR position at all commanded positions, go to step 4.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S16643120952001102400000).
4. Turn ignition off. Disconnect EGR valve connector. see scheme 6 Turn ignition on. Using a test light connected to ground, probe terminal "E" (White wire) at EGR valve harness connector. see scheme 11 Using scan tool, command EGR 0-10 percent. If test light turns on and off with each command, go to next step. If test light does not turn on and off with each command, go to step 13.
5. Turn ignition off, then back on. Using scan tool, observe EGR position sensor parameter. If EGR position sensor is zero percent, go to next step. If EGR position sensor is not zero percent, go to step 9.
6. Measure voltage between terminal "B" (Black wire) and terminal "D" (Gray wire) at EGR valve harness connector. see scheme 11 If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 8.
7. Connect a 3-amp fused jumper wire between terminal "D" (Gray wire) and terminal "C" (Brown wire) at EGR valve harness connector. Using scan tool, observe EGR position sensor parameter. If EGR position sensor is about 100 percent, go to step 14. If EGR position is not about 100 percent, go to step 11.
8. Measure voltage between ground and terminal "D" (Gray wire) at EGR valve harness connector. see scheme 11 If voltage is about 5 volts, go to step 10. If voltage is not about 5 volts, go to step 12.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "C" (Brown wire) at EGR valve harness connector. If any voltage is indicated, repair short to voltage in Brown wire between EGR valve and PCM. After repairs, go to step 18. If no voltage is indicated, go to step 15.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black wire between terminal "B" at EGR valve harness connector and terminal No. 31 at PCM C1 harness connector. see scheme 2and see scheme 11. If continuity does not exist, repair open in Black wire. After repairs, go to step 18. If continuity exists, go to step 15.
11. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal "C" (Brown wire) at EGR valve harness connector. see scheme 11 If test light illuminates, repair short to ground in Brown wire between EGR valve and PCM. After repairs, go to step 18. If test light does not illuminate, go to step 15.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check 5-volt reference circuit (Gray wire) as follows: Check for open or short to ground in Gray wire between terminal "D" at EGR valve harness connector and terminal No. 30 at PCM C2 harness connector. see scheme 2and see scheme 11. Turn ignition on. Using a test light connected to ground, probe terminal No. 30 (Gray wire) at PCM C2 harness connector. Test light should not illuminate. If test light illuminates, Gray wire is shorted to voltage. If any problems are found, repair as necessary. After repairs, go to step 18. If no problems are found, go to step 15.
13. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal "E" (White wire) at EGR valve harness connector. see scheme 11 If test light illuminates, repair short to ground in White wire between EGR valve and PCM. After repairs, go to step 18. If test light does not illuminate, go to step 15.
14. Check for poor connections at EGR valve connector. Repair connector as necessary. After repairs, go to step 18. If connector is okay, go to step 16.
15. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 18. If connectors are okay, go to step 17.
16. Replace EGR valve. After repairs, go to step 18.
17. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
18. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Remove EGR valve and inspect for deposits that may interfere with EGR valve pintle extending completely or cause pintle to stick. If problem is intermittent, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. NOTE: If DTC P1635 is set, diagnose DTC before continuing with this test. See «DTC P1635: 5-VOLT REFERENCE "A" CIRCUIT»(ref-126121-S35998884072001102400000).
2. Ensure ignition is on. Using scan tool, observe EGR valve position sensor voltage. If voltage is less than.14 volt, go to step 4. If voltage is.14 volt or more, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault my be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect EGR valve connector. see scheme 6 Connect a 3-amp fused jumper wire between terminal "C" (Brown wire) and terminal "D" (Gray wire) at EGR valve harness connector. see scheme 11 Turn ignition on. Using scan tool, observe EGR position sensor parameter. If EGR position sensor is about 100 percent, remove jumper wire and go to step 10. If EGR position is not about 100 percent, remove jumper wire and go to next step.
5. Measure voltage between ground and terminal "D" (Gray wire) at EGR valve harness connector. If voltage is about 5 volts, go to step 9. If voltage is not about 5 volts, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Gray wire between terminal "D" at EGR valve harness connector and terminal No. 30 at PCM C2 harness connector. see scheme 2and see scheme 11. If continuity does not exist, repair open in Gray wire. After repairs, go to step 15. If continuity exists, go to next step.
7. Using a test light connected to positive battery voltage, probe terminal No. 30 (Gray wire) at PCM C2 harness connector. see scheme 2 If test light illuminates, repair short to ground in Gray wire between PCM and EGR valve. After repairs, go to step 15. If test light does not illuminate, go to next step.
8. Ensure ignition is off. Reconnect PCM connectors. Connect DVOM between terminal "B" (Black wire) and terminal "D" (Gray wire) at EGR valve harness connector. Observe DVOM and disconnect Throttle Position (TP) sensor, and then Manifold Absolute Pressure (MAP) sensor. A voltage change indicates a faulty sensor. If any problems are found, replace TP sensor or MAP sensor as necessary. After repairs, go to step 15. If no problems are found, go to step 11.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in EGR valve position signal circuit (Brown wire) between terminal "C" at EGR valve harness connector and terminal No. 28 at PCM C2 harness connector. see scheme 2and see scheme 11. If any problems are found, repair as necessary. After repairs, go to step 15. If no problems are found, go to step 11.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for continuity between terminal "C" (Brown wire) and terminal "E" (White wire) at EGR valve harness connector. If continuity exists, Brown wire is shorted to White wire. Repair wiring as necessary. After repairs, go to step 15. If continuity does not exist, go to step 12.
11. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 15. If connectors are okay, go to step 14.
12. Check for poor connections at EGR valve connector. Repair connector as necessary. After repairs, go to step 15. If connector is okay, go to step 13.
13. Replace EGR valve. After repairs, go to step 15.
14. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
15. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
16. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Low system airflow can cause an intermittent condition. Check AIR system for pinched, kinked, restricted, or leaking pipes, hoses or fittings. Check for restricted AIR pump inlet duct/hose/filter. AIR pump is located if left front of engine compartment, mounted to subframe. Check for pinched, kinked, restricted, or leaking vacuum lines. Check components for heat damage. If heat damage is indicated, replace AIR shutoff valve on the bank that damage is present. Right (rear) AIR shutoff valve is mounted to front of right (rear) cylinder head. Left (front) AIR shutoff valve is mounted to rear of left (front) cylinder head.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, command AIR solenoid on and off. AIR solenoid is located next to intake manifold, near right (rear) cylinder head. If AIR solenoid turns on and off with each command, no problem is indicated. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If AIR solenoid does not turn on and off with each command, go to next step.
3. Disconnect AIR solenoid. Ensure ignition is on. Using a test light connected to ground, probe terminal No. 1 (Pink/Black wire) at AIR solenoid harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 10.
4. Connect a test light between terminals No. 1(Pink/Black wire) and No. 2 (Pink/Black wire) at AIR solenoid harness connector. Using scan tool, command AIR solenoid on and off. If test light turns on and off with each command, go to next step. If test light does not turn on and off with each command, go to next step.
5. If test light remains illuminated with each command, go to step 7. If test light does not remain illuminated with each command, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to voltage in Pink/Black wire between terminal No. 2 at AIR solenoid harness connector and terminal No. 45 at PCM C1 harness connector. see scheme 2and (Scheme 25). If any problems are found, repair as necessary. After repairs, go to step 13. If no problems are found, go to step 9.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal No. 45 (Pink/Black wire) at PCM C1 harness connector. see scheme 2 If test light illuminates, repair short to ground in Pink/Black wire between PCM and AIR solenoid. After repairs, go to step 13. If test light does not illuminate, go to step 12.
8. Check for poor connections at AIR solenoid connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to step 11.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 13. If connectors are okay. go to step 12.
10. Repair Pink/Black wire between terminal No. 1 at AIR solenoid and fuse No. 11 (IGN 1 fuse) in underhood fuse block. After repairs, go to step 13.
11. Replace AIR solenoid. After repairs, go to step 13.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, command AIR pump relay on and off. If AIR pump relay turns on and off with each command, no problem is indicated. Fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If AIR pump relay does not turn on and off with each command, go to next step.
3. Turn ignition off. Disconnect AIR pump relay. see scheme 12 Turn ignition on. Using a test light connected to ground, probe Pink/Black wire at AIR pump relay harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 10.
4. Connect a test light between Pink/Black and Brown wires at AIR pump relay harness connector. Using scan tool, command AIR pump and AIR solenoid on and off. If test light turns on and off with each command, go to step 8. If test light does not turn on and off with each command, go to next step.
5. If test light remains illuminated with each command, go to step 7. If test light does not remain illuminated with each command, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to voltage in Brown wire between AIR pump relay harness connector and terminal No. 75 at PCM C2 harness connector. see scheme 2 If any problems are found, repair as necessary. After repairs, go to step 13. If no problems are found, go to step 9.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal No. 75 (Brown wire) at PCM C2 harness connector. If test light does not illuminate, go to step 9. If test light illuminates, repair short to ground in Brown wire between PCM and AIR pump relay. After repairs, reconnect all components. Using scan tool, command AIR pump and AIR solenoid on and off. If AIR pump does not operate, replace AIR pump. After repairs, go to step 13.
8. Check for poor connections at AIR pump relay connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to step 11.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 13. If connectors are okay. go to step 12.
10. Repair Pink/Black wire between AIR pump relay and fuse No. 11 (IGN 1 fuse) in underhood fuse block. After repairs, go to step 13.
11. Replace AIR pump relay. After repairs, go to step 13.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If any other DTCs are set, diagnose DTCs before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If no other DTCs are set, go to next step. NOTE: In the following step, if A/C clutch cycles, diagnostic test will abort.
3. Using scan tool, clear DTCs. Turn A/C off. Start engine. Ensure engine is at normal operating temperature. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, no problem is indicated at this time. Test is complete. If DTC resets, go to next step. Diagnostic test may need to be completed up to 6 times in order to pass or fail. If more than 6 tests have been attempted and DTC has not passed or failed this ignition cycle, test may be aborting. See «DIAGNOSTIC AIDS»(ref-126121-S37285237452001102400000) .
4. Ensure original 3-way catalytic converter is installed correctly. Check catalytic converter for damage, severe discoloration or tampering. If any problems are found, go to step 7 . If no problems are found, go to next step.
5. Check exhaust system for leaks, damage, and loose or missing hardware. Repair exhaust system as necessary. After repairs, go to step 8 . If exhaust system is okay, go to next step.
6. Ensure oxygen sensors are properly installed and wiring and connections are okay. If any problems are found, repair as necessary. After repairs, go to step 8 . If no problems are found, go to next step.
7. Replace catalytic converter. After repairs, go to next step. NOTE: A misfire condition may damage replacement catalytic converter. Check for misfire condition and repair as necessary before replacing catalytic converter.
8. Turn ignition off. Reconnect all disconnected connectors. Using scan tool, clear DTCs. Turn A/C off. Start engine. Ensure engine is at normal operating temperature. Operate vehicle within conditions for running the DTC as specified in code enable criteria. Diagnostic test may need to be completed up to 6 times in order to pass or fail. If more than 6 tests have been attempted and DTC has not passed or failed this ignition cycle, test may be aborting. See «DIAGNOSTIC AIDS»(ref-126121-S37285237452001102400000) . If DTC runs and passes, go to next step. If DTC resets, go to step 4 .
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

The PCM will not enable the catalyst test until the following conditions are met

1. Engine speed is plus or minus 100 RPM from desired idle speed.
2. Throttle position is zero percent.
3. Short term integrator is -20 to +20 percent.

The catalyst test will abort if the vehicle falls outside the following conditions while the test is running

1. Engine speed is plus or minus 125 RPM from desired idle speed.
2. Throttle position is zero percent.
3. Short term integrator is -20 to +20 percent.

Catalyst test may abort because of a change in engine load. If a load change occurs during the test, repeat test. More than 6 tests may have to be attempted to get 6 completed tests. An aborted test counts as an attempted test. The number of attempted tests is limited to 12 per ignition cycle. After a return to idle, the HO2S bank 1 sensor 1 signal may stay rich or lean for several seconds, and cause the test to be delayed. Check for faulty connections at the PCM. Inspect wiring harness for damage. If wiring harness appears to be okay, observe scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate location of the fault.

Note. EVAP Pressure/Purge Diagnostic Station (J 41413) is required to pressurize EVAP system in the following test.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0443 or DTC P0449 is also set, see «DTC P0443: EVAPORATIVE EMISSION PURGE VALVE 1 CONTROL CIRCUIT»(ref-126121-S28527405032001102400000) or «DTC P0449: EVAPORATIVE EMISSION VENT VALVE CONTROL CIRCUIT»(ref-126121-S37369516542001102400000). If DTC P0443 or DTC P0449 is not set, go to next step.
3. Inspect EVAP system for the following conditions. Check for loose, missing or damaged service port Schrader valve. Check for loose, incorrect, missing or damaged fuel filler cap. Check for damaged EVAP canister purge valve. see scheme 6 Raise and support vehicle. Check for disconnected, improperly routed, kinked or damaged EVAP pipes and hoses. Check for damaged EVAP canister vent valve. EVAP canister vent valve is located near fuel tank. (Scheme 26) Check for damaged EVAP canister. EVAP canister is located near fuel tank. (Scheme 27) If any problems are found, repair as necessary. After repairs, go to 17. If no problems are found, go to next step.
4. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415). Connect EVAP Pressure/Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Monitor pressure gauge for one minute. If pressure stays at 5 in. H2O, go to next step. If pressure does not stay at 5 in. H2O, go to step 7.
5. Using scan tool, observe Fuel Tank Pressure (FTP) sensor value. Compare EVAP pressure/purge diagnostic station value to scan tool FTP sensor value. If EVAP pressure/purge diagnostic station value is near scan tool value, go to next step. If EVAP pressure/purge diagnostic station value is not near scan tool value, go to step 11.
6. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Disconnect EVAP purge pipe from EVAP canister purge valve. see scheme 6 If EVAP system pressure decreases, go to step 8. If EVAP system pressure does not decrease, go to step 9.
7. Using EVAP pressure/purge diagnostic station, continuously pressurize EVAP system. Using Ultrasonic Leak Detector (J 41416) check EVAP system for leaks. Carefully leak test all EVAP system hoses, tubes and connections. It may be necessary to partially lower fuel tank to inspect components located in upper portion of fuel tank. If any leaks are found, repair as necessary. After repairs, go to step 17. If no leaks are found, see «DIAGNOSTIC AIDS»(ref-126121-S09205614942001102400000).
8. Connect a vacuum gauge to EVAP purge valve purge pipe port. Start engine and allow it to idle. Using scan tool, command EVAP canister purge valve to 50 percent. If vacuum gauge indicates an increase in vacuum, see «DIAGNOSTIC AIDS»(ref-126121-S09205614942001102400000). If vacuum gauge does not indicate an increase in vacuum, go to step 14.
9. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Disconnect purge pipe from EVAP canister. (Scheme 27) If EVAP system pressure decreases, go to step 15. If EVAP system pressure does not decrease, go to next step.
10. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Disconnect vapor pipe from EVAP canister. If EVAP system pressure decreases, go to 16. If EVAP system pressure does not decrease, go to step 13.
11. Using scan tool, monitor FTP sensor voltage. If voltage is more than 4.3 volts, go to «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT HIGH VOLTAGE»(ref-126121-S11304510612001102400000). If voltage is 4.3 volts or less, go to next step.
12. Replace FTP sensor. FTP sensor is located on top of fuel tank and can be accessed through an inspection panel in trunk. After repairs, go to step 17.
13. Repair pinched or obstructed EVAP vapor pipe. After repairs, go to step 17.
14. Replace EVAP canister purge valve. After repairs, go to step 17.
15. Repair restriction in EVAP purge pipe. After repairs, go to step 17.
16. Replace EVAP canister. After repairs, go to next step.
17. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Monitor pressure gauge for 5 minutes. If pressure stays at 5 in. H2O, go to next step. If pressure does not stay at 5 in. H2O, go to step 7.
18. Monitor pressure gauge on EVAP pressure/purge diagnostic station. Using scan tool, command EVAP purge valve to 50 percent. If EVAP system pressure decreases, go to next step. If EVAP system pressure does not decrease, go to step 9.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Use EVAP Pressure/Purge Diagnostic Station (J 41413) to pressurize EVAP system to aid in locating intermittent leaks. Move all EVAP components while testing with Ultrasonic Leak Detector (J 41416). A temporary blockage in EVAP canister purge valve, purge pipe or EVAP canister could cause an intermittent condition. Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to set occurs. This may assist in diagnosing condition.

Scheme 25

Scheme 26

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0443 or DTC P0449 is also set, see «DTC P0443: EVAPORATIVE EMISSION PURGE VALVE 1 CONTROL CIRCUIT»(ref-126121-S28527405032001102400000) or «DTC P0449: EVAPORATIVE EMISSION VENT VALVE CONTROL CIRCUIT»(ref-126121-S37369516542001102400000). If DTC P0443 or DTC P0449 is not set, go to next step.
3. Inspect EVAP system for the following conditions. Check for loose, missing or damaged service port Schrader valve. Check for loose, incorrect, missing or damaged fuel filler cap. Check for damaged EVAP canister purge valve. see scheme 6 Raise and support vehicle. Check for disconnected, improperly routed, kinked or damaged EVAP pipes and hoses. Check for damaged EVAP canister vent valve. EVAP canister vent valve is located near fuel tank. (Scheme 26) Check for damaged EVAP canister. EVAP canister is located near fuel tank. (Scheme 27) If any problems are found, repair as necessary. After repairs, go to 6. If no problems are found, go to next step.
4. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415). Connect EVAP Pressure/Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Monitor pressure gauge for one minute. If pressure stays at 5 in. H2O, go to «DIAGNOSTIC AIDS»(ref-126121-S14046730402001102400000). If pressure does not stay at 5 in. H2O, go to next step.
5. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415). Connect EVAP Pressure/Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, continuously pressurize system to 15 in. H2O. Using Ultrasonic Leak Detector (J 41416) check EVAP system for leaks. Carefully leak test all EVAP system hoses, tubes and connections. It may be necessary to partially lower fuel tank to inspect components located in upper portion of fuel tank. If any leaks are found, repair as necessary. After repairs, go to next step. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S14046730402001102400000).
6. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415). Connect EVAP Pressure/Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Monitor pressure gauge for one minute. If pressure stays at 5 in. H2O, go to next step. If pressure does not stay at 5 in. H2O, go to step 2.
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

EVAP system tests run when engine is first started and meets code enable criteria for this DTC. Use EVAP Pressure/Purge Diagnostic Station (J 41413) to pressurize EVAP system to aid in locating intermittent leaks. Move all EVAP components while testing with Ultrasonic Leak Detector (J 41416).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Turn ignition on. Using scan tool, command EVAP canister purge valve to 50 percent, and then to zero percent. If a clicking noise is felt or heard from EVAP canister purge valve when commanded to 50 percent, go to next step. see scheme 6 If a clicking noise is not felt or heard from EVAP canister purge valve when commanded to 50 percent, go to step 4.
3. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Ensure engine is idling. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect EVAP purge valve connector. Turn ignition on. Using a test light connected to ground, probe Pink/White wire at EVAP purge valve harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11.
5. Connect a test light between Pink/White and Dark Green/White wires at EVAP purge valve harness connector. Using scan tool, command EVAP canister purge valve to zero percent. If test light illuminates, go to step 9. If test light does not illuminate, go to next step.
6. Using scan tool, command EVAP canister purge valve to 50 percent. If test light illuminates or pulses, go to step 8. If test light does not illuminate or pulse, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to voltage in Dark Green/White wire between EVAP canister purge valve harness connector and terminal No. 76 at PCM C1 harness connector. see scheme 2 If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Using a test light connected to positive battery voltage, probe Dark Green/White wire at EVAP canister purge valve harness connector. If test light illuminates, repair short to ground in Dark Green/White wire between EVAP canister purge valve and PCM. After repairs, go to step 14. If test light does not illuminate, go to step 13.
9. Check for poor connections at EVAP purge valve connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
11. Repair open or short to ground in power circuit (Pink/White wire) to EVAP canister purge valve. Also check fuse No. 11 (IGN 1 fuse) in underhood fuse block. After repairs, go to step 14.
12. Replace EVAP canister purge valve. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Note. EVAP Pressure/Purge Diagnostic Station (J 41413) is required to pressurize EVAP system in the following test.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0443, P0449, P0452 or P0543 is also set, repair DTC(s) before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000). If DTC P0443, P0449, P0452 or P0543 is not set, go to next step.
3. Check for damaged EVAP canister vent valve or pinched EVAP canister vent valve hose. EVAP canister vent valve is located near fuel tank. (Scheme 26) If any problems are found, repair as necessary. After repairs, go to 14. If no problems are found, go to next step.
4. Disconnect purge line from EVAP canister purge valve. see scheme 6 Ensure ignition is on. Using scan tool, observe fuel tank pressure parameter. If scan tool indicates fuel tank pressure is about zero in. H2O, go to next step. If scan tool does not indicate fuel tank pressure is about zero in. H2O, go to step 8.
5. Turn ignition off. Reconnect all connectors and components. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure/Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, command EVAP vent valve ON. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Using scan tool, command EVAP vent valve OFF. If fuel tank pressure changes to zero in. H2O, no problem is indicated. Fault may be intermittent. See «DIAGNOSTIC AIDS»(ref-126121-S03045703542001102400000). If fuel tank pressure does not change to zero in. H2O, go to step 7.
6. While observing scan tool, disconnect vent hose from EVAP canister vent valve. (Scheme 26) If fuel tank pressure changes to zero in. H2O, go to step 10. If fuel tank pressure does not change to zero in. H2O, go to next step.
7. Disconnect vent hose/pipe from EVAP canister. (Scheme 27) If fuel tank pressure changes to zero in. H2O, go to step 13. If fuel tank pressure does not change to zero in. H2O, go to step 11.
8. Using scan tool, monitor FTP sensor voltage. If voltage is more than 4.3 volts, go to «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT HIGH VOLTAGE»(ref-126121-S11304510612001102400000). If voltage is 4.3 volts or less, go to next step.
9. Check for poor connections at FTP sensor connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
10. Replace EVAP canister vent valve. After repairs, go to step 14.
11. Replace EVAP canister. After repairs, go to step 14.
12. Replace FTP sensor. FTP sensor is located on top of fuel tank and can be accessed through an inspection panel in trunk. After repairs, go to step 14.
13. Repair pinched or obstructed EVAP vent hose/pipe. After repairs, go to next step.
14. Turn ignition off. Reconnect all connectors and components. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure/Purge Station (J 41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, command EVAP vent valve ON. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Using scan tool, command EVAP vent valve OFF. If fuel tank pressure changes to zero in. H2O, go to next step. If fuel tank pressure does not change to zero in. H2O, go to step 3.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent valve inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, command EVAP vent valve ON and OFF. If a clicking noise is felt or heard from EVAP vent valve, go to next step. EVAP canister vent valve is located near fuel tank. (Scheme 26) If a clicking noise is not felt or heard from EVAP vent valve, go to step 4.
3. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
4. Turn ignition off. Disconnect EVAP vent valve connector. Turn ignition on. Using a test light connected to ground, probe Pink wire at EVAP vent valve harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11.
5. Connect a test light between Pink and White wires at EVAP vent valve harness connector. Using scan tool, command EVAP vent valve ON and OFF. If test light turns on and off with each command, go to step 9. If test light does not turn on and off with each command, go to next step.
6. If test light remains on with each command, go to step 8. If test light does not remain on with each command, go to next step.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to voltage in White wire between EVAP canister vent valve harness connector and terminal No. 2 at PCM C2 harness connector. see scheme 2 If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Using a test light connected to positive battery voltage, probe White wire at EVAP canister vent valve harness connector. If test light illuminates, repair short to ground in White wire between EVAP canister vent valve and PCM. After repairs, go to step 14. If test light does not illuminate, go to step 10.
9. Check for poor connections at EVAP vent valve connector. Repair connector as necessary. After repairs, go to step 14. If connector is okay, go to step 12.
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
11. Repair open or short to ground in power circuit (Pink wire) to EVAP canister vent valve. Also check fuse No. 11 (VENT SOL fuse) in rear fuse block. Rear fuse block is located underneath driver's side rear seat. After repairs, go to step 14.
12. Replace EVAP canister vent valve. After repairs, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P1639 is also set, go to «DTC P1639: 5-VOLT REFERENCE "B" CIRCUIT»(ref-126121-S25007490172001102400000). If DTC P1639 is not set, go to next step.
3. Ensure ignition is on. Using scan tool, observe FTP sensor voltage. If voltage is less than.1 volt, go to step 5. If voltage is.1 volt or more, go to next step.
4. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
5. Turn ignition off. Disconnect FTP sensor. FTP sensor is located on top of fuel tank and can be accessed through an inspection panel in trunk. Turn ignition on. Connect a jumper wire between terminal "B" (Gray wire) and terminal "C" (Dark Green wire) at FTP sensor harness connector. (Scheme 23) Using scan tool, observe FTP sensor voltage. If voltage is about 5 volts, go to step 9. If voltage is not about 5 volts, go to next step.
6. Remove jumper wire. Connect a DVOM between terminal "A" (Black wire) and terminal "B" (Gray wire) at FTP sensor harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 8.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor connections at PCM and FTP sensor connectors. Repair connectors as necessary. If connectors are okay, check FTP sensor signal circuit (Dark Green wire) as follows: Check continuity of Dark Green wire between terminal "C" at FTP sensor harness connector and terminal No. 55 at PCM C2 harness connector. see scheme 2and (Scheme 23). Continuity should exist. If continuity does not exist, Dark Green wire is open. Check for continuity between terminal "A" (Black wire) and terminal "C" (Dark Green wire) at FTP sensor harness connector. Continuity should not exist. If continuity exists, White and Dark Green wires are shorted together. Using a test light connected to positive battery voltage, probe terminal "C" (Dark Green wire) at FTP sensor harness connector. Test light should not illuminate. If test light illuminates, Dark Green wire is shorted to ground. If any problems are found, repair as necessary. After repairs, go to step 12. If no problems are found, go to step 11.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor connections at PCM and FTP sensor connectors. Repair connectors as necessary. If connectors are okay, check continuity of Gray wire between terminal "B" at FTP sensor harness connector and terminal No. 34 at PCM C2 harness connector. see scheme 2and (Scheme 23). If continuity does not exist, repair open in Gray wire. After repairs, go to step 12. If continuity exists, go to step 11.
9. Check for poor connections at FTP sensor connector. Repair connector as necessary. After repairs, go to step 12. If connector is okay, go to next step.
10. Replace FTP sensor. After repairs, go to step 12.
11. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
12. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
13. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P1639 is also set, go to «DTC P1639: 5-VOLT REFERENCE "B" CIRCUIT»(ref-126121-S25007490172001102400000). If DTC P1639 is not set, go to next step.
3. If DTC P0463 is also set, go to next step. If DTC P10463 is not also set, go to step 6.
4. Turn ignition off. Disconnect FTP sensor connector. Connect a test light between positive battery voltage and terminal "A" (Black wire) at FTP sensor harness connector. (Scheme 23) Turn ignition on. If test light illuminates, go to step 11. If test light does not illuminate, go to next step.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor connections at PCM connectors. Repair connectors as necessary. If connectors are okay, check continuity of Black wire between terminal "A" at FTP sensor harness connector and terminal No. 28 at PCM C1 harness connector. see scheme 2and (Scheme 23). If continuity does not exist, repair open in Black wire. After repairs, go to step 10. If continuity exists, go to step 12.
6. Turn ignition on. Using scan tool, observe FTP sensor voltage. If voltage is more than 4.7 volts, go to step 8. If voltage is 4.7 volts or less, go to next step.
7. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, fault may be intermittent. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.
8. Turn ignition off. Disconnect FTP sensor. FTP sensor is located on top of fuel tank and can be accessed through an inspection panel in trunk. Turn ignition on. Using scan tool, observe FTP sensor voltage. If voltage is about zero volts, go to step 11. If voltage is not about zero volts, go to next step.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for poor connections at PCM connectors. Repair connectors as necessary. If connectors are okay, check for continuity between terminal "B" (Gray wire) and terminal "C" (Dark Green wire) at FTP sensor harness connector. (Scheme 23) If continuity exists, Dark Green and Gray wires are shorted together. Repair wiring as necessary. After repairs, go to step 13. If continuity does not exist, go to step 12.
10. Check for poor connections at FTP sensor connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to step 11.
11. Replace FTP sensor. After repairs, go to step 13.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If engine cooling diagnostic system check has already been performed, go to next step. If engine cooling diagnostic system check has not been perform, go to «ENGINE COOLING DIAGNOSTIC SYSTEM CHECK»(ref-126121-S27365484032001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Ensure ignition is on. Using scan tool, command low speed fans on and off. If cooling fan 1 relay turns on and off with each command, see «DIAGNOSTIC AIDS»(ref-126121-S05256730612001102400000). Cooling fan 1 relay is located in underhood fuse block. If cooling fan 1 relay does not turn on and off with each command, go to next step.
3. Turn ignition off. Remove cooling fan 1 relay. Turn ignition on. Using a test light connected to ground, probe battery voltage circuit at cooling fan 1 relay connector in underhood fuse block. See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 8.
4. Connect test light between cooling fan 1 relay control circuit (Dark Green wire) and battery voltage circuit at cooling fan 1 relay connector in underhood fuse block. Using scan tool, command low speed fans on and off. If test light turns on and off with each command, go to step 10. If test light does not turn on and off with each command, go to next step.
5. If test light remains illuminated with each command, go to step 7. If test light does not remain illuminated with each command, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check control circuit (Dark Green wire) for cooling fan 1 relay as follows: Check continuity of Dark Green wire between cooling fan 1 relay connector in underhood fuse block and terminal No. 25 at PCM C1 harness connector. see scheme 2 Continuity should exist. If continuity does not exist, Dark Green wire is open. Turn ignition on. Measure voltage between ground and terminal No. 25 (Dark Green wire) at PCM C1 harness connector. If any voltage is indicated, Dark Green wire is shorted to voltage between PCM and cooling fan 1 relay connector in underhood fuse block. If any problems are found, repair wiring as necessary. After repairs, go to step 14. If no problems are found, go to step 9.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal No. 25 (Dark Green wire) at PCM C1 harness connector. see scheme 2 If test light illuminates, repair short to ground in Dark Green wire between PCM and cooling fan 1 relay connector in underhood fuse block. After repairs, go to step 14. If test light does not illuminate, go to step 9.
8. Turn ignition off. Check for an open or short to ground in cooling fan relay 1 battery voltage circuit between fuse No. 47 and cooling fan relay 1 connector at underhood fuse block. If any problems are found, repair as necessary. After repairs, go to step 14. If no problems are found, go to step 11.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 14. If connectors are okay, go to step 13.
10. Turn ignition off. Check for poor connections at cooling fan 1 relay connector in underhood fuse block. Repair connector as necessary. After repairs, go to step 14. If connectors are okay, go to step 12.
11. Repair short to ground in cooling fan motor supply voltage circuit (Gray wire). After repairs, go to step 14.
12. Replace cooling fan 1 relay. After replacing relay, go to step 14.
13. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
14. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
15. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection. Review FREEZE/FAILURE RECORDS vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

1. If engine cooling diagnostic system check has already been performed, go to next step. If engine cooling diagnostic system check has not been perform, go to «ENGINE COOLING DIAGNOSTIC SYSTEM CHECK»(ref-126121-S27365484032001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Ensure ignition is on. Using scan tool, command high speed fans on and off. If cooling fan S/P relay and cooling fan 2 relay turn on and off with each command, see «DIAGNOSTIC AIDS»(ref-126121-S36948074042001102400000). Cooling fan S/P relay and cooling fan 2 relay are located in underhood fuse block. If cooling fan S/P relay and cooling fan 2 relay do not turn on and off with each command, go to next step.
3. Turn ignition off. Remove cooling fan 2 relay. Turn ignition on. Using a test light connected to ground, probe battery voltage circuit at cooling fan 2 relay connector in underhood fuse block. See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 8.
4. Connect test light between cooling fan 2 relay control circuit (Dark Blue wire) and battery voltage circuit at cooling fan 2 relay connector in underhood fuse block. Using scan tool, command high speed fans on and off. If test light turns on and off with each command, go to step 9. If test light does not turn on and off with each command, go to next step.
5. If test light remains illuminated with each command, go to step 7. If test light does not remain illuminated with each command, go to next step.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check control circuit (Dark Blue wire) for cooling fan 2 relay as follows: Check continuity of Dark Blue wire between cooling fan 2 relay connector in underhood fuse block and terminal No. 5 at PCM C1 harness connector. see scheme 2 Also check continuity of Dark Blue wire between cooling fan S/P relay connector in underhood fuse block and terminal No. 5 at PCM C1 harness connector. Both readings should indicate continuity exists. If continuity does not exist, Dark Blue wire is open. Turn ignition on. Measure voltage between ground and terminal No. 5 (Dark Blue wire) at PCM C1 harness connector. If any voltage is indicated, Dark Blue wire is shorted to voltage between PCM and cooling fan 2 relay or cooling fan S/P relay connector in underhood fuse block. If any problems are found, repair wiring as necessary. After repairs, go to step 12. If no problems are found, go to step 9.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal No. 5 (Dark Blue wire) at PCM C1 harness connector. see scheme 2 If test light illuminates, repair short to ground in Dark Blue wire between PCM and cooling fan 2 relay connector or cooling fan S/P relay in underhood fuse block. After repairs, go to step 12. If test light does not illuminate, go to step 9.
8. Turn ignition off. Check for an open or short to ground in battery voltage circuit for cooling fan S/P relay and cooling fan relay 2 in underhood fuse block. If any problems are found, repair as necessary. After repairs, go to step 12. If no problems are found, go to step 10.
9. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 12. If connectors are okay, go to step 11.
10. Repair short to ground in cooling fan motor supply voltage circuit (Light Blue wire). After repairs, go to step 12.
11. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
12. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
13. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection. Review FREEZE/FAILURE RECORDS vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Set parking brake and block drive wheels. Start engine. Turn all accessories off. Using scan tool RPM control function, slowly increment engine speed to 1800 RPM, then to 600 RPM, then back to 1800 RPM. Exit RPM control function. If engine speed stabilizes within 75 RPM of commanded RPM, go to next step. If engine speed does not stabilize within 75 RPM of commanded RPM, go step 4.
3. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S35579002202001102400000).
4. Turn ignition off. Disconnect IAC valve connector. Connect IAC Motor Driver (J 37027-A) to IAC valve. Start engine. Using IAC motor driver, command IAC valve in until about 600 RPM is reached, then command IAC valve out until about 1800 RPM is reached. Return engine speed to desired idle as indicated on scan tool data list. If engine speed steadily decreased to about 600 RPM, and then steadily increased to about 1800 RPM when IAC valve was commanded, go to next step. If engine speed did not steadily decrease to about 600 RPM, and then steadily increase to about 1800 RPM when IAC valve was commanded, go to step 11.
5. Using a test light connected to ground, probe any IAC valve circuit at IAC valve harness connector using Connector Test Adapter Kit (J 36616). Start engine. Using IAC motor driver, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM while observing a scan tool until IAC counts start to increment. Observe test light while IAC counts are incrementing. Return engine idle speed to desired idle as indicated on scan tool data list. Repeat procedure for remaining 3 IAC valve circuits. If test light remained on, (never flashed) while IAC counts were incrementing at any IAC valve circuit, go to step 10. If test light did not remain on, (never flashing) while IAC counts were incrementing at any IAC valve circuit, go to next step.
6. If test light remained off (never flashed), go to step 9. If test light did not remain off, go to next step.
7. Using connector test kit adapter, connect a test light between terminal "C" (Light Blue/Black wire) and terminal "D" (Light Blue/White wire) at IAC valve harness connector. see scheme 16 Using IAC motor driver, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM while observing scan tool until IAC counts start to increment. Observe test light while IAC counts are incrementing. Return engine idle speed to desired idle as indicated on scan tool data list. Repeat procedure with test light connected between terminal "A" (Light Green/Black wire) and terminal "B" (Light Green/White wire) at IAC valve harness connector. Return engine speed to desired idle as indicated on scan tool data list. If test light remained on (never flashing) while IAC counts where incrementing during test, go to next step. If test light did not remain on (never flashing) while IAC counts where incrementing during test, go to step 15.
8. Check for poor connections at IAC valve connector. Repair connector as necessary. After repairs, go to step 16. If connectors are okay, see «DIAGNOSTIC AIDS»(ref-126121-S35579002202001102400000).
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a DVOM, check for an open or short ground on IAC valve circuit where test light remained off. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 12.
10. Turn ignition on. Using a DVOM, check for short to voltage on IAC valve circuit where test light remained illuminated. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 12.
11. Visually and physically inspect for the following: Throttle body damage and tampering. Throttle lever screw tampering, if equipped. Restricted air intake system. Inspect for a possible collapsed or clogged air intake duct before and after air filter element, restricted air filter element, or restriction at throttle body intake screen, if equipped. Remove IAC valve. Inspect for the following: A clogged IAC passage. Excessive deposits on throttle plate. Excessive deposits in throttle bore. Excessive deposits on IAC valve pintle. If any problems are found, repair as necessary. After repairs, go to step 16. If no problems are found, go to step 13.
12. Check for poor connections at PCM connectors. Repair connector as necessary. After repairs, go to step 16. If connectors are okay, go to step 15.
13. Check for poor connections at IAC valve connector. Repair connector as necessary. After repairs, go to step 16. If connector is okay, go to next step.
14. Replace IAC valve. After repairs, go to step 16.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Inspect for the following conditions

1. Check for restricted air intake system.
2. Check for collapsed, clogged, or loose air intake ducts, clogged air filter, and proper operation of mass airflow sensor.
3. Check for a tampered or damaged throttle stop screw.
4. Check for a tampered or damaged throttle plate, throttle shaft, or throttle linkage.
5. Check for objects blocking IAC passage or throttle bore.
6. Check for excessive deposits in IAC passage or on IAC pintle. Check for excessive deposits in throttle bore or on throttle plate.
7. Check for vacuum leaks.
8. A low or unstable idle condition could be caused by a non-IAC system problem that cannot be overcome by IAC valve. See SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article.

Scheme 27

1. If engine electrical diagnostic system check has already been performed, go to next step. If engine electrical diagnostic system check has not been performed, go to «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(ref-126121-S25464916142001110500000) under DIAGNOSTIC SYSTEM CHECKS.
2. Ensure ignition is on. Using scan tool, observe IGNITION 1 signal voltage parameter in PCM data list. If voltage is more than 11 volts, go to step 6. If voltage is 11 volts or less, go to next step.
3. Check battery voltage and compare voltage reading with ignition 1 signal voltage parameter in PCM data list. If voltages differ by more than.5 volt, go to next step. If voltages does not differ by more than.5 volt, diagnose charging system and repair as necessary.
4. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for high resistance in battery voltage supply circuit (Orange wire) to terminal No. 20 at PCM C1 harness connector and terminal No. 21 at PCM C2 harness connector. see scheme 2 If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to next step.
5. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 7. If connectors are okay, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If engine electrical diagnostic system check has already been performed, go to next step. If engine electrical diagnostic system check has not been performed, go to «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(ref-126121-S25464916142001110500000) under DIAGNOSTIC SYSTEM CHECKS.
2. Ensure ignition is on. Using scan tool, observe IGNITION 1 signal voltage parameter in PCM data list. If voltage is more than 10 volts, go to step 6. If voltage is 10 volts or less, go to next step.
3. Check battery voltage and compare voltage reading with ignition 1 signal voltage parameter in PCM data list. If voltages differ by more than.5 volt, go to next step. If voltages does not differ by more than.5 volt, diagnose charging system and repair as necessary.
4. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for high resistance in battery voltage supply circuit (Orange wires) to terminal No. 20 at PCM C1 harness connector and terminal No. 21 at PCM C2 harness connector see scheme 2 If any problems are found, repair as necessary. After repairs, go to step 7. If no problems are found, go to next step.
5. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 7. If connectors are okay, go to next step.
6. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
7. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If engine electrical diagnostic system check has already been performed, go to next step. If engine electrical diagnostic system check has not been performed, go to «ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK»(ref-126121-S25464916142001110500000) under DIAGNOSTIC SYSTEM CHECKS.
2. Ensure ignition is on. Using scan tool, observe IGNITION 1 signal voltage parameter in PCM data list. If voltage is 16 volts or more, go to next step. If voltage is less than 16 volts, go to step 4 .
3. Check battery voltage and compare voltage reading with ignition 1 signal voltage parameter in PCM data list. If voltages differ by more than .5 volt, go to next step. If voltages does not differ by more than .5 volt, diagnose charging system and repair as necessary.
4. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . After repairs, go to next step.
5. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
6. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) .

DTC P0601 indicates that contents of EEPROM have changed since PCM was programmed. PCM must be replaced and reprogrammed.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Reprogram PCM using correct software. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . If DTC P0602 resets, go to next step.
3. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) .

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Using scan tool, command MIL on and off. If MIL turns on and off, see «DIAGNOSTIC AIDS»(ref-126121-S30498879182001110600000). If MIL does not turn of and off, go to next step.
3. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal No. 5 (Brown/White wire) at PCM C2 harness connector. see scheme 2 If battery voltage is present, go to next step. If battery voltage is not present, go to step 7.
4. Connect DVOM between ground and terminal No. 5 (Brown/White wire) at PCM C2 harness connector. Monitor current reading for at least 2 minutes. If current reading remains 5-50 milliamps, go to step 12. If current reading does not remain 5-50 milliamps, go to next step.
5. Turn ignition off. Ensure PCM is disconnected. Remove Instrument Panel Cluster (IPC). See REMOVAL & INSTALLATION in appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Turn ignition on. Measure voltage between ground and terminal No. 5 (Brown/White wire) at PCM C2 harness connector. If any voltage is indicated, go to next step. If no voltage is indicated, go to step 11.
6. Repair short to voltage in Brown/White wire between PCM and instrument cluster. After repairs, go to step 16.
7. Turn ignition off. Remove and inspect fuse No. 12 (IGN 1 fuse) from rear fuse block. Rear fuse block is located underneath driver's side rear seat. If fuse is okay, reinstall fuse and go to step 9. If fuse is blown, go to next step.
8. Repair short to ground in Pink wire between IPC and rear fuse block. Replace fuse. After repairs, go to step 16.
9. Turn ignition off. Remove Instrument Panel Cluster (IPC). See REMOVAL & INSTALLATION in appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Turn ignition on. Measure voltage between ground and terminal B4 (Pink wire) at IPC C2 harness connector. see scheme 3 If battery voltage is present, go to next step. If battery voltage is not present, go to step 14.
10. Check for an open or short to ground in Brown/White wire between terminal B1 at IPC C2 harness connector and terminal No. 5 at PCM C2 harness connector. If any problems are found, repair wiring as necessary. After repairs, go to step 16. If no problems are found, go to next step.
11. Check for poor connections at IPC C2 harness connector and PCM C2 harness connector. Repair connectors as necessary. After repairs, go to step 16. If connectors are okay, perform instrument cluster diagnostic system check. See INSTRUMENT CLUSTER DIAGNOSTIC SYSTEM CHECK in appropriate ANALOG INSTRUMENT PANELS article.
12. Turn ignition off. Reconnect PCM connectors. Remove Instrument Panel Cluster (IPC). See REMOVAL & INSTALLATION in appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Turn ignition on. Connect a test light between terminal B1 (Brown/White wire) and terminal B4 (Pink wire) at IPC C2 harness connector. see scheme 3 Using scan tool, command MIL on and off. If test light turns on and off, see «DIAGNOSTIC AIDS»(ref-126121-S30498879182001110600000). If test light does not turn on and off, go to next step.
13. Check for poor connection at terminal No. 5 (Brown/White wire) at PCM C2 harness connector. Repair connector as necessary. After repairs, go to step 16. If connector is okay, go to step 15.
14. Repair open in Pink wire between terminal B4 at IPC C2 harness connector and fuse No. 12 in rear fuse block. After repairs, go to step 16.
15. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to step 16.
16. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

MIL is actually a Light Emitting Diode (LED). A LED requires a parallel dropping resistor to operate on a 12-volt system. If LED burns out, the dropping resistor will still pass voltage on to the PCM, and the DTC P0650 may not set even though the MIL is inoperative. If the power supply circuit to the indicator lights and the MIL control circuit check out okay, the IPC needs to be checked for a faulty LED. See INSTRUMENT CLUSTER DIAGNOSTIC SYSTEM CHECK in appropriate ANALOG INSTRUMENT PANELS article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine. Using scan tool, check for any other DTCs that are set. If DTC P1635 or P0108 is not set, go to next step. If DTC P1635 or P0108 is set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).
3. Using scan tool, observe MAP sensor voltage. If voltage is more than 4.2 volts, go to step 5. If voltage is 4.2 volts or less, go next step.
4. Using scan tool, observe MAP sensor voltage while wiggling MAP sensor connector, PCM connectors and relate wiring harnesses. see scheme 6 PCM is located in engine compartment, inside air filter housing. If voltage is more than 4.2 volts, go to next step. If voltage is 4.2 volts or less, see «DIAGNOSTIC AIDS»(ref-126121-S32840817542001102400000).
5. Turn ignition off. Disconnect MAP sensor connector. Turn ignition on. Using scan tool, observe MAP sensor voltage. If voltage is less than.1 volt, go to next step. If voltage is.1 volt or more, go to step 8.
6. Measure voltage between Gray and Orange/Black wires at MAP sensor harness connector. If voltage is 4.7-5.2 volts, go to step 11. If voltage is not 4.7-5.2 volts, go to next step.
7. If voltage was more than 5.2 volts in previous step, go to step 10. If voltage was less than 4.7 volts in previous step, go to step 9.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Light Green wire at MAP sensor harness connector. If any voltage is indicated, repair short to voltage in Light Green wire between MAP sensor and PCM. After repairs, go to step 13. If no voltage is indicated, go to step 12.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Orange/Black wire between MAP sensor harness connector and terminal No. 13 at PCM C1 harness connector. see scheme 2 If continuity does not exist, repair open in Orange/Black wire. After repairs, go to step 13. If continuity exists, go to step 12.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and Gray wire at MAP sensor harness connector. If any voltage is indicated, repair short to voltage in Gray wire between MAP sensor and PCM. After repairs, go to step 13. If no voltage is indicated, go to step 12.
11. Check for poor connections at MAP sensor connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, see «DIAGNOSTIC AIDS»(ref-126121-S32840817542001102400000).
12. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to next step. If connectors are okay, see «DIAGNOSTIC AIDS»(ref-126121-S32840817542001102400000).
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Check MAP sensor vacuum source for leaks, restrictions and poor connections. If condition is still intermittent, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine. Using scan tool, check for any other DTCs that are set. If DTC P1635 or P0107 is not set, go to next step. If DTC P1635 or P0107 is set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).
3. Using scan tool, observe MAP sensor voltage. If voltage is less than.1 volt, go to step 5. If voltage is.1 volt or more, go next step.
4. Using scan tool, observe MAP sensor voltage while wiggling MAP sensor connector, PCM connectors and relate wiring harnesses. see scheme 6 PCM is located in engine compartment, inside air filter housing. If voltage is less than.1 volt, go to next step. If voltage is.1 volt or more, see «DIAGNOSTIC AIDS»(ref-126121-S35303019332001102400000).
5. Turn ignition off. Disconnect MAP sensor connector. Turn ignition on. Using scan tool, observe MAP sensor voltage. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 7.
6. Connect a 3-amp fused jumper wire between Gray and Light Green wires at MAP sensor harness connector. Using scan tool, observe MAP sensor voltage. If voltage is about 5 volts, go to step 9. If voltage is not about 5 volts, disconnect jumper wire and go to step 8.
7. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in 5-volt reference circuit (Gray wire) between MAP sensor harness connector and terminal No. 10 at PCM C1 harness connector. see scheme 2 If any problems are found, repair as necessary. After repairs, go to step 11. If no problems are found, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check for an open or short to ground in signal circuit (Light Green wire) between MAP sensor harness connector and terminal No. 25 at PCM C2 harness connector. see scheme 2 If any problems are found, repair as necessary. After repairs, go to step 11. If no problems are found, go to step 10.
9. Check for poor connections at MAP sensor connector. Repair connector as necessary. After repairs, go to step 11. If connector is okay, see «DIAGNOSTIC AIDS»(ref-126121-S35303019332001102400000).
10. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to next step. If connectors are okay, see «DIAGNOSTIC AIDS»(ref-126121-S35303019332001102400000).
11. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
12. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Check MAP sensor vacuum source for leaks, restrictions and poor connections. If condition is still intermittent, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0113 is also set, go to «DTC P0113: INTAKE AIR TEMPERATURE SENSOR CIRCUIT HIGH VOLTAGE»(ref-126121-S20676744482001102400000). If DTC P0113 is not also set, go to next step.
3. If DTC P1106, P1115 and/or P1121 is also set, go to step 6. If DTC P1106, P1115 and/or P1121 is not also set, go to next step.
4. Check for poor ground circuit terminal contact (Red/Black wire) at IAT sensor connector. Repair connector as necessary. After repairs, go to step 10. If connector is okay, go to next step.
5. Check for poor signal circuit terminal contact (Tan wire) at IAT sensor connector. Repair connector as necessary. After repairs, go to step 10. If connector is okay, go to step.
6. Ensure ignition is off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Disconnect IAT sensor connector. While wiggling wiring harness, check continuity of Tan wire between IAT sensor harness connector and terminal No. 50 at PCM C2 harness connector. see scheme 2 If continuity changes while wiggling wiring harness, repair open in Tan wire. After repairs, go to step 10. If continuity exists, go to next step.
7. Turn ignition off. While wiggling wiring harness, measure voltage between ground and terminal No. 50 (Tan wire) at PCM C2 harness connector. If any voltage exists while wiggling wiring harness, repair short to voltage in Tan wire. After repairs, go to step 10. If no voltage exists, go to next step.
8. Check for poor connection at terminal No. 17 (Red/Black wire) at PCM C1 harness connector. Repair connector as necessary. After repairs, go to step 10. If connector is okay, go to next step.
9. While wiggling wiring harness, check continuity of Red/Black wire between IAT sensor harness connector and terminal No. 17 at PCM C1 harness connector. If continuity changes while wiggling wiring harness, repair open in Red/Black wire. After repairs, go to step 10. If continuity exists, see «DIAGNOSTIC AIDS»(ref-126121-S41584161812001110600000).
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Check for a faulty connection at PCM or IAT sensor. Check wiring harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, or poor terminal-to-wire connection. Check for damaged wiring harness. If wiring harness appears to be okay, observe IAT display on scan tool while moving connectors and wiring harnesses related to IAT sensor. A change in IAT display will indicate location of the malfunction. A skewed IAT sensor may cause this DTC to set. Check IAT sensor resistance at specified temperature. See INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. If DTC P1111 cannot be duplicated, information included in failure records can be useful in determining vehicle mileage since the diagnostic test last failed. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0112 is also set, go to «DTC P0112: INTAKE AIR TEMPERATURE SENSOR CIRCUIT LOW VOLTAGE»(ref-126121-S29001454162001102400000) . If DTC P0112 is not also set, go to next step.
3. Ensure ignition is off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Disconnect IAT sensor connector. Using a test light connected to positive battery voltage, probe Tan wire at IAT sensor harness connector while wiggling wiring harness. Test light should not illuminate. If test light illuminates while wiggling wiring harness, Tan wire is shorted to ground. Repair wiring harness as necessary. After repairs, go to next step. If wiring harness is okay, see «DIAGNOSTIC AIDS»(ref-126121-S17784130942001110600000) .
4. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
5. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

Check for a faulty connection at PCM or IAT sensor. Check wiring harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, or poor terminal-to-wire connection. Check for damaged wiring harness. If wiring harness appears to be okay, observe IAT display on scan tool while moving connectors and wiring harnesses related to IAT sensor. A change in IAT display will indicate location of the malfunction. A skewed IAT sensor may cause this DTC to set. Check IAT sensor resistance at specified temperature. See INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. If DTC P1112 cannot be duplicated, information included in failure records can be useful in determining vehicle mileage since the diagnostic test last failed. If an intermittent condition exists, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine. Check for any other DTCs that are set. If DTC P0117 is also set, go to «DTC P0117: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT LOW VOLTAGE»(ref-126121-S36307404732001102400000). If DTC P0117 is not also set, turn ignition off and go to next step.
3. Turn ignition on. Using scan tool, observe ECT sensor temperature. Wiggle ECT sensor and PCM connectors. (Scheme 24) PCM is located in engine compartment, inside air filter housing. If scan tool indicates a change in temperature, go to step 6. If scan tool does not indicate a change in temperature, go to next step
4. Turn ignition on. Using scan tool, observe ECT sensor temperature. Wiggle wiring harness between ECT sensor and PCM connectors. If scan tool indicates a change in temperature, go to step 7. If scan tool does not indicate a change in temperate, go to next step
5. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, see «DIAGNOSTIC AIDS»(ref-126121-S38597653782001110600000). If DTC does not reset, no problem is indicated. Test is complete.
6. Repair connector terminals as necessary. After repairs, go to step 8.
7. Repair wiring harness where temperature change was indicated. After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

An intermittent short to ground in ECT sensor signal circuit could result in a DTC P1114. If ECT low voltage reading is present, additional sensor circuit voltage codes could be set. Refer to any non-intermittent DTCs that are set. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . A skewed ECT sensor may cause this DTC to set. Check ECT sensor resistance at specified temperature. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE table.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine. Check for any other DTCs that are set. If DTC P0118 is also set, go to «DTC P0118: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT HIGH VOLTAGE»(ref-126121-S02607154252001102400000). If DTC P0118 is not also set, turn ignition off and go to next step.
3. Turn ignition on. Using scan tool, observe ECT sensor temperature. Wiggle ECT sensor and PCM connectors. (Scheme 24) PCM is located in engine compartment, inside air filter housing. If scan tool indicates a change in temperature, go to step 6. If scan tool does not indicate a change in temperature, go to next step.
4. Turn ignition on. Using scan tool, observe ECT sensor temperature. Wiggle wiring harness between ECT sensor and PCM connectors. If scan tool indicates a change in temperature, go to step 7. If scan tool does not indicate a change in temperate, go to next step.
5. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, see «DIAGNOSTIC AIDS»(ref-126121-S36326495282001110600000). If DTC does not reset, no problem is indicated. Test is complete.
6. Repair connector terminals as necessary. After repairs, go to step 8.
7. Repair wiring harness where temperature change was indicated. After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

An intermittent open or short to voltage in ECT sensor signal circuit could result in a DTC P1115. If ECT high voltage reading is present, additional sensor circuit voltage codes could be set. Refer to any non-intermittent DTCs that are set. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . A skewed ECT sensor may cause this DTC to set. Check ECT sensor resistance at specified temperature. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE table.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition off. Disconnect TP sensor connector. Connect a DVOM between ground and 5-volt reference circuit (Gray wire) at TP sensor harness connector. Turn ignition on. Lightly wiggle related engine wiring harnesses and connectors for all 5-volt reference circuits while observing voltage reading. See WIRING DIAGRAMS article. Any change in voltage indicates area where a short to voltage may exist. If voltage changes, repair wiring or connectors as necessary. After repairs, go to step 9 . If voltage does not change, go to next step.
3. Connect a DVOM between ground and signal circuit (Dark Blue wire) at TP sensor harness connector. Lightly wiggle related engine wiring harnesses and connectors while observing voltage reading. Any change in voltage indicates area where a short to voltage may exist. If voltage changes, repair wiring or connectors as necessary. After repairs, go to step 9 . If voltage does not change, go to next step.
4. Turn ignition off. Measure resistance between ground and low reference circuit (Black wire) at TP sensor harness connector. Lightly wiggle related engine wiring harnesses and connectors while observing resistance reading. Any change in resistance indicates area where an open or high resistance may exist. If resistance changes, repair wiring or connectors as necessary. After repairs, go to step 9 . If resistance does not change, go to next step.
5. Check for poor connections at TP sensor connector. Repair connector as necessary. After repairs, go to step 9 . If connector is okay, go to next step.
6. Check for poor connections at PCM connectors. PCM is located in engine compartment, inside air filter housing. Repair connectors as necessary. After repairs, go to step 9 . If connectors are okay, go to next step.
7. Connect one end of a jumper wire to Dark Blue wire at TP sensor harness connector and other end to DVOM. Using a second jumper wire, connect one end to Gray wire at TP sensor harness connector and other end to DVOM. Set DVOM to 40-k/ohms scale. Ensure jumper wires have a good connection at TP sensor and DVOM test leads. Press MIN MAX button on DVOM. Slowly depress accelerator pedal to Wide Open Throttle (WOT) and then back to closed throttle position several times. Press MIN MAX button, and record MAX reading. Press MIN MAX button again, and record MIN reading. Disconnect jumper wire from Gray wire, and reconnect jumper wire to Black wire at TP sensor harness connector. Press MIN MAX button on DVOM. Slowly depress accelerator pedal to WOT and back to closed throttle position several times. Press MIN MAX button, and record MAX reading. Press MIN MAX button again, and record MIN reading. If a MAX value of OL, or a MIN value of zero ohms is recorded in either test, go to next step. If a MAX value of OL, or a MIN value of zero ohms is not recorded in either test, no problem is indicated. Diagnose by symptom. See SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article.
8. Replace TP sensor. After repairs, go to next step.
9. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
10. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition off. Disconnect TP sensor connector. Connect a DVOM between ground and 5-volt reference circuit (Gray wire) at TP sensor harness connector. Turn ignition on. Lightly wiggle related engine wiring harnesses and connectors for all 5-volt reference circuits while observing voltage reading. See WIRING DIAGRAMS article. Any change in voltage indicates area where an intermittent open, high resistance or short to ground may exist. If voltage changes, repair wiring or connectors as necessary. After repairs, go to step 8 . If voltage does not change, go to next step.
3. Connect a DVOM between ground and signal circuit (Dark Blue wire) at TP sensor harness connector. Turn ignition on. Lightly wiggle related engine wiring harnesses and connectors while observing voltage reading. Any change in voltage indicates area where an intermittent open, high resistance or short to ground may exist. If voltage changes, repair wiring or connectors as necessary. After repairs, go to step 8 . If voltage does not change, go to next step.
4. Check for poor connections at TP sensor connector. Repair connector as necessary. After repairs, go to step 8 . If connector is okay, go to next step.
5. Check for poor connections at PCM connectors. PCM is located in engine compartment, inside air filter housing. Repair connectors as necessary. After repairs, go to step 8 . If connectors are okay, go to next step.
6. Connect one end of a jumper wire to Dark Blue wire at TP sensor harness connector and other end to DVOM. Using a second jumper wire, connect one end to Gray wire at TP sensor harness connector and other end to DVOM. Set DVOM to 40-k/ohms scale. Ensure jumper wires have a good connection at TP sensor and DVOM test leads. Press MIN MAX button on DVOM. Slowly depress accelerator pedal to Wide Open Throttle (WOT) and then back to closed throttle position several times. Press MIN MAX button, and record MAX reading. Press MIN MAX button again, and record MIN reading. Disconnect jumper wire from Gray wire, and reconnect jumper wire to Black wire at TP sensor harness connector. Press MIN MAX button on DMM. Slowly depress accelerator pedal to WOT and back to closed throttle position several times. Press MIN MAX button, and record MAX reading. Press MIN MAX button again, and record MIN reading. If a MAX value of OL, or a MIN value of zero ohms is recorded in either test, go to next step. If a MAX value of OL, or a MIN value of zero ohms is not recorded in either test, no problem is indicated. Diagnose by symptom. See SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article.
7. Replace TP sensor. After repairs, go to next step.
8. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
9. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Using scan tool, clear DTCs. Reset the fuel trim values. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor HO2S bank 1 sensor 1voltage. If HO2S voltage is fixed within 351-551 millivolts, go to step 4. If HO2S voltage is not fixed within 351-551 millivolts, go to next step.
3. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: HO2S bank 1 sensor 1 connector water intrusion. An intermittently open HO2S bank 1 sensor 1 high signal circuit (Purple wire). An intermittently open HO2S bank 1 sensor 1 low reference circuit (Black wire). High resistance in HO2S bank 1 sensor 1 low reference circuit (Black wire). PCM ground circuits with high resistance to ground. An inoperative HO2S bank 1 sensor 1 heater. Poor HO2S or PCM connector terminal contact. An exhaust system leak, typically within 12" upstream of HO2S bank 1 sensor 1. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 17. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S25817198862001102900000).
4. Turn ignition off. Disconnect HO2S bank 1 sensor 1 connector. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) Connect another jumper wire between ground and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 harness connector. Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is less than 20 millivolts, go to step 7. If voltage is 20 millivolts or more, go to next step.
5. Turn ignition off. Disconnect jumper wires. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Purple wire between terminal No. 10 at PCM C2 harness connector and terminal "B" at HO2S bank 1 sensor 1 harness connector. see scheme 2and (Scheme 21). Also check continuity of Black wire between terminal "A" at HO2S bank 1 sensor 1 harness connector and terminal No. 28 at PCM C1 harness connector. If all resistance readings are less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, go to step 9.
6. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 17. If connectors are okay, go to next step.
7. Disconnect jumper wires. Connect a test light between terminal "C" (Black/White wire) and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. Start engine and observe test light. If test light illuminates, go to next step. If test light does not illuminate, go to step 10.
8. Turn ignition off. Reconnect HO2S bank 1 sensor 1 connector. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 12. If resistance is 500 ohms or more, go to step 11.
9. Repair open in Black or Purple wire between HO2S bank 1 sensor 1 and PCM. After repairs, go to step 17.
10. Repair open or high resistance in Pink/White wire between HO2S bank 1 sensor 1 and fuse No. 20 (OXY SEN fuse) in underhood fuse block, or repair open in Black/White wire between HO2S bank 1 sensor 1 and terminal No. 37 at PCM C2 harness connector. Also check fuse No. 20 (OXY SEN fuse) in underhood fuse block. After repairs, go to step 17.
11. Repair high resistance between HO2S bank 1 sensor 1 low reference circuit (Black wire) and PCM ground circuit (Black/White wire). Possible causes include the following: Poor HO2S bank 1 sensor 1 connector terminal contact. Faulty HO2S bank 1 sensor 1. Poor PCM ground connection. High PCM ground circuit resistance. Ungrounded exhaust system. Repair as necessary. After repairs, go to step 17.
12. Check for exhaust leaks upstream of HO2S bank 1 sensor 1. Leak may be very small and within 12" of HO2S bank 1 sensor 1. Repair exhaust system as necessary. After repairs, go to step 17. If exhaust system is okay, go to next step.
13. Allow engine to cool to ambient temperature. Recheck continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 15. If resistance is 500 ohms or more, go to next step.
14. Remove HO2S bank 1 sensor 1. Clean HO2S bank 1 sensor 1 threads. Apply anti-seize to HO2S bank 1 sensor 1 threads and reinstall sensor. Tighten sensor to 30 ft. lbs. (41 N.m). Recheck continuity between terminals No. 16 (Black/White wire) and No. 28 (Black wire) at PCM C1 harness connector. If resistance is less than 500 ohms, go to step 17. If resistance is 500 ohms or more, go to next step.
15. Replace HO2S bank 1 sensor 1. After repairs, go to step 17.
16. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
17. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
18. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

A malfunction in the HO2S heater ignition feed or ground circuit may cause DTC to set. Check HO2S heater circuits for intermittent malfunctions or poor connections. If connections and wiring are okay and the DTC continues to set, HO2S may be at fault. Review failure records vehicle mileage since the diagnostic test last failed to determine how often condition occurs that caused DTC to set. This may assist in diagnosing condition.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0140 is also set, go to step 4. If DTC P0140 is not also set, go to next step.
3. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000). If no other DTCs are set, go to step 5.
4. HO2S bank 1 sensor 1 is contaminated. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S bank 1 sensor 1. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) After repairs, go to step 18.
5. Using scan tool, clear DTCs. Reset fuel trim values. Start engine. Start engine. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. If DTC resets, go to step 7. If DTC does not reset, go to next step.
6. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions: An exhaust system leak between engine and HO2S bank 1 sensor 1. HO2S bank 1 sensor 1 connector water intrusion. Poor HO2S or PCM connector terminal contact. A loose HO2S bank 1 sensor 1. Tighten sensor to 30 ft. lbs. (41 N.m). An inoperative HO2S bank 1 sensor 1 heater. An intermittently open or shorted HO2S bank 1 sensor 1 high signal circuit (Purple wire). An intermittently open or shorted HO2S bank 1 sensor 1 low reference circuit (Black wire). Contaminated fuel. Excessive engine oil or coolant consumption. Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step 18. If no problems are found, see «DIAGNOSTIC AIDS»(ref-126121-S00132415552001110600000).
7. Check for exhaust leaks between engine and HO2S bank 1 sensor 1. HO2S bank 1 sensor 1 is located in right (rear) exhaust manifold. (Scheme 22) Repair exhaust leaks as necessary. Check for poor connections at HO2S bank 1 sensor 1 connector and PCM connectors. PCM is located in engine compartment, inside air filter housing. If any problems are found, repair connectors as necessary. After repairs, go to step 18. If connectors are okay, go to next step.
8. Turn ignition off. Connect a jumper wire between ground and terminal "A" (Black wire) at HO2S bank 1 sensor 1 harness connector. (Scheme 21) Turn ignition on. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is 351-551 millivolts, go to next step. If voltage is not 351-551 millivolts, go to step 13.
9. Connect another jumper wire between ground and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 harness connector. Using scan tool, observe HO2S bank 1 sensor 1 voltage. If voltage is less than 20 millivolts, go to next step. If voltage is 20 millivolts or more, go to step 14.
10. Disconnect jumper wire from terminal "A" (Black wire) at HO2S bank 1 sensor 1 harness connector. Ensure ignition is on. Connect a test light between ground and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 15.
11. Disconnect jumper wires. Connect a test light between terminal "C" (Black/White wire) and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 harness connector. Start engine and observe test light. If test light illuminates, go to next step. If test light does not illuminate, go to step 16.
12. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. After repairs, go to step 17.
13. Turn ignition off. Check HO2S bank 1 sensor 1 high signal circuit (Purple wire) as follows: Check for a short to ground in Purple wire between terminal "B" at HO2S bank 1 sensor 1 and terminal No. 10 at PCM C2 harness connector. see scheme 2and (Scheme 21). Check if terminal "A" (Black wire) and terminal "B" (Purple wire) at HO2S bank 1 sensor 1 are shorted together. Check if terminal "B" (Purple wire) and terminal "D" (Pink/White wire) at HO2S bank 1 sensor 1 are shorted together. Repair wiring as necessary. After repairs, go to step 18.
14. Check for an open or high resistance in Purple wire between terminal "B" at HO2S bank 1 sensor 1 and terminal No. 10 at PCM C2 harness connector. see scheme 2and (Scheme 21). Also check for an open or high resistance in Black wire between terminal "A" at HO2S bank 1 sensor 1 and terminal No. 28 at PCM C1 harness connector. Repair wiring as necessary. After repairs, go to step 18.
15. Repair open or high resistance in Pink/White wire between terminal "D" at HO2S bank 1 sensor 1 and fuse No. 20 (OXY SEN fuse) in underhood fuse block. Also check fuse No. 20 (OXY SEN fuse) in underhood fuse block. After repairs, go to step 18.
16. Repair open or high resistance in Black/White wire between terminal "C" at HO2S bank 1 sensor 1 and terminal No. 37 at PCM C2 harness connector. see scheme 2and (Scheme 21). After repairs, go to step 18.
17. Replace HO2S bank 1 sensor 1. After repairs, go to next step.
18. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

A malfunction in the HO2S heater ignition feed or ground circuit may cause DTC to set. Check HO2S heater circuits for intermittent malfunctions or poor connections. If connections and wiring are okay and the DTC continues to set, HO2S may be at fault. Review failure records vehicle mileage since the diagnostic test last failed to determine how often condition occurs that caused DTC to set. This may assist in diagnosing condition.

1. If engine cooling diagnostic system check has already been performed, go to next step. If engine cooling diagnostic system check has not been perform, go to «ENGINE COOLING DIAGNOSTIC SYSTEM CHECK»(ref-126121-S27365484032001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Check cooling fan operation. If cooling fans are not functioning properly, diagnose cooling fans as necessary. See ELECTRIC COOLING FANS - CARS article in ENGINE COOLING. If cooling fans are functioning properly, diagnose cooling system and repair as necessary.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Perform CKP system variation learn procedure. See «CRANKSHAFT POSITION SENSOR SYSTEM VARIATION LEARN PROCEDURE»(ref-126121-S09213767522001102400000) under PROGRAMMING. After procedure is complete, go to next step.
3. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

CKP system variation compensating values are stored in PCM memory after a learn procedure has been performed. If actual crankshaft position system variation is not within CKP system variation compensating values stored in PCM, DTC P0300 may set. See DIAGNOSTIC AIDS in DTC P0300: ENGINE MISFIRE DETECTED.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Start engine. Allow engine to reach normal operation temperature. Using scan tool, monitor specific DTC information for DTC P1372. If DTC P1372 sets, turn ignition off and go to step 4 . If DTC P1372 does not set, go to next step.
3. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S20651277052001102400000) .
4. Turn ignition on. Using scan tool, command TIME MODE B. Start engine. Raise and support vehicle. Wiggle CKP sensor wiring harness and connector. CKP sensor is located above starter motor and has a 6-pin connector. Using scan tool, monitor specific DTC information for DTC P0385. If DTC P0385 sets, go to «P0385: CRANKSHAFT POSITION SENSOR "B" CIRCUIT»(ref-126121-S06044544312001102400000) . If DTC P0385 does not set, turn ignition off and go to next step.
5. Turn ignition on. Using scan tool, command TIME MODE A. Ensure engine is still idling. Wiggle CKP sensor wiring harness and connector. Using scan tool, monitor specific DTC information for DTC P0335. If DTC P0335 sets, go to «DTC P0335: CRANKSHAFT POSITION SENSOR "A" CIRCUIT»(ref-126121-S06044544312001102400000) . If DTC P0335 does not set, go to next step.
6. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

When diagnosing CKP sensors, it may be necessary to enable a specific decode mode (ANGLE, TIME A or TIME B). In order to enable a specific crank decode, use scan tool and perform the following

1. Turn ignition on.
2. Select ENGINE OUTPUT CONTROLS.
3. Select CRANK POSITION SENSING DECODE mode.
4. Select desired mode (ANGLE, TIME A or TIME B) by pressing SELECT STATE.
5. Command decode mode by pressing COMMAND STATE.

The commanded state remains valid for current ignition cycle. A specific decode mode cannot be commanded with engine running, or after commanding a desired decode mode. In order to command a different decode mode, ignition must be cycled off and on. For intermittent faults, see INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.

If powertrain diagnostic system check has already been performed, perform anti-lock brake diagnostic system check. See DIAGNOSTIC SYSTEM CHECK in ANTI-LOCK/TCS - BOSCH 5.3 - C, G, H & K BODIES article in BRAKES. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK under DIAGNOSTIC SYSTEM CHECKS.

If DTC P1380 is set, it indicates that ABS/TCS system has detected a malfunction which will not allow the EBTCM to transmit correct rough road data to the PCM.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Ensure ignition is on. Using scan tool, select CHASSIS APPLICATION and attempt to display ABS data. If ABS data can be displayed, no problem is indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If ABS data cannot be displayed, perform anti-lock brake diagnostic system check. See DIAGNOSTIC SYSTEM CHECK in ANTI-LOCK/TCS - BOSCH 5.3 - C, G, H & K BODIES article in BRAKES.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS. NOTE: If DTC P0403 is set, diagnose DTC before continuing with this test. See «DTC P0403: EXHAUST GAS RECIRCULATION SOLENOID CONTROL CIRCUIT»(ref-126121-S04118872412001102400000).
2. Ensure ignition is on. Using scan tool, check EGR position sensor parameter. If scan tool indicates zero percent, go to next step. If scan tool does not indicate zero percent, go to step 5.
3. Using scan tool, command EGR valve from zero percent to 100 percent. If desired EGR position remains close to EGR position sensor at all commanded positions, go to next step. If desired EGR position does not remain close to EGR position sensor at all commanded positions, go to step 6.
4. Using scan tool, observe and record FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria, or as close to recorded FREEZE FRAME/FAILURE RECORDS data as possible. If DTC resets, go to next step. If DTC does not reset, see «DIAGNOSTIC AIDS»(ref-126121-S31734428062001102400000).
5. Disconnect EGR valve connector. see scheme 6 Turn ignition on. Using scan tool, observe EGR position sensor parameter. If scan tool indicates zero percent, go to next step. If scan tool does not indicate zero percent, go to step 9.
6. Measure voltage between terminal "B" (Black wire) and terminal "D" (Gray wire) at EGR valve harness connector. see scheme 11 If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 8.
7. Connect a 3-amp fused jumper wire between terminal "C" (Brown wire) and terminal "D" (Gray wire) at EGR valve harness connector. Using scan tool, observe EGR position sensor parameter. If EGR position sensor is about 100 percent, disconnect jumper wire and go to step 13. If EGR position is not about 100 percent, disconnect jumper wire and go to step 11.
8. Measure voltage between ground and terminal "D" (Gray wire) at EGR valve harness connector. see scheme 11 If voltage is about 5 volts, go to step 10. If voltage is not about 5 volts, go to step 12.
9. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Measure voltage between ground and terminal "C" (Brown wire) at EGR valve harness connector. If any voltage is indicated, repair short to voltage in Brown wire between EGR valve and PCM. After repairs, go to step 17. If no voltage is indicated, go to step 14.
10. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity of Black wire between terminal "B" at EGR valve harness connector and terminal No. 31 at PCM C1 harness connector. see scheme 2and see scheme 11. If continuity does not exist, repair open in Black wire. After repairs, go to step 17. If continuity exists, go to step 14.
11. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal "C" (Brown wire) at EGR valve harness connector. see scheme 11 If test light illuminates, repair short to ground in Brown wire between EGR valve and PCM. After repairs, go to step 17. If test light does not illuminate, go to step 15.
12. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check 5-volt reference circuit (Gray wire) as follows: Check for open or short to ground in Gray wire between terminal "D" at EGR valve harness connector and terminal No. 30 at PCM C2 harness connector. see scheme 2and see scheme 11. Turn ignition on. Using a test light connected to ground, probe terminal No. 30 (Gray wire) at PCM C2 harness connector. Test light should not illuminate. If test light illuminates, Gray wire is shorted to voltage. If any problems are found, repair wiring as necessary. After repairs, go to step 17. If no problems are found, go to step 15.
13. Check for poor connections at EGR valve connector. Repair connector as necessary. After repairs, go to step 17. If connector is okay, go to step 16.
14. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step 17. If connectors are okay, go to step 16.
15. Replace EGR valve. After repairs, go to step 17.
16. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
17. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
18. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Check for excessive deposits on EGR valve pintle and seat. Remove EGR valve and check for deposits that may interfere with EGR valve pintle extending completely or cause pintle to stick.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0443, P0449, P0452 or P0453 is also set, diagnose DTC(s) before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000). If DTC P0443, P0449, P0452 or P0453 is not also set, go to next step.
3. Remove fuel fill cap. Ensure ignition is on. Using scan tool, monitor fuel tank pressure. If fuel tank pressure is -.5 to +.5 in. H2O, go to next step. If fuel tank pressure is not -.5 to +.5 in. H2O, go to «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT HIGH VOLTAGE»(ref-126121-S11304510612001102400000).
4. Disconnect EVAP purge pipe from EVAP canister purge valve. see scheme 6 Install a vacuum gauge to EVAP canister purge valve purge port. Disconnect EVAP canister purge valve connector. Monitor vacuum on vacuum gauge. Start engine and allow it to idle. Increase engine speed 1200-1500 RPM. If vacuum gauge indicates an increase in vacuum, go to next step. If vacuum gauge does not indicate an increase in vacuum, see «DIAGNOSTIC AIDS»(ref-126121-S05982446612001102400000).
5. Replace EVAP canister purge valve. After repairs, go to next step.
6. Using scan tool, monitor fuel tank pressure. Start engine and allow it to idle for 30 seconds. If fuel tank pressure is -.5 to +.5 in. H2O, go to next step. If fuel tank pressure is not -.5 to +.5 in. H2O, go to step 3.
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

An intermittent condition could be caused by an improperly installed or damaged EVAP canister purge valve or by a temporary blockage in EVAP canister purge valve.

1. If air conditioning diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «AIR CONDITIONING DIAGNOSTIC SYSTEM CHECK»(ref-126121-S00049102342001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Using scan tool, select DIM A/C information from data list. Using scan tool, observe evaporator temperature parameter. If scan indicates temperature is -34 to 261°F (-37 to 127°C), no problem is indicated at this time. Fault may be intermittent. If scan does not indicate temperature is -34 to 261°F (-37°C to 127°C), go to next step.
3. Turn ignition off. Disconnect A/C refrigerant low temperature sensor. Sensor is located in suction hose of A/C compressor and has a 2-pin connector with Black/White and Gray wires. Turn ignition on. Using scan tool, observe evaporator temperature parameter. If scan tool indicates temperature is less than -34°F (37°C), go to next step. If scan tool does not indicate temperature is less than -34°F (37°C), go to 5.
4. Turn ignition off. Connect a 3-amp fused jumper wire between Black/White and Gray wires at A/C refrigerant low temperature sensor harness connector. Turn ignition on. Using scan tool, observe evaporator temperature parameter. If scan tool indicates temperature is more than 261°F (127°C), go to step 8. If scan tool does not indicate temperature is more than 261°F (127°C), go to step 6.
5. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe Gray wire at A/C refrigerant low temperature sensor harness connector. If test light illuminates, repair short to ground in Gray wire between A/C refrigerant low temperature sensor and DIM. After repairs, go to step 12. If test light does not illuminate, go to step 9.
6. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Measure voltage between ground and Gray wire at A/C refrigerant low temperature sensor harness connector. If any voltage is indicated, repair short to voltage in Gray wire between A/C refrigerant low temperature sensor and DIM. After repairs, go to step 12. If no voltage is indicated, go to next step.
7. Check continuity of Black/White wire between A/C refrigerant low temperature sensor harness connector and terminal A6 at DIM C2 harness connector. see scheme 18 If continuity does not exist, repair open in Black/White wire. After repairs, go to step 12. If continuity exists, go to step 9.
8. Check for poor connections A/C refrigerant low temperature sensor connector. Repair connector as necessary. After repairs, go to step 12. If connector is okay, go to step 10.
9. Check for poor connections at DIM connectors. Repair connectors as necessary. After repairs, go to step 12. If connectors are okay, go to step 11.
10. Replace A/C refrigerant low temperature sensor. See REMOVAL & INSTALLATION in AUTOMATIC A/C-HEATER SYSTEMS - AURORA article in AIR CONDITIONING & HEATING. After repairs, go to step 12.
11. Replace DIM. See REMOVAL & INSTALLATION in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs, go to next step.
12. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
13. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Scheme 28

If DTC P1536 is stored as a history code, it indicates that the DIM did receive a high engine coolant temperature message from the PCM. Interrupting A/C compressor operation can occur as a normal function to protect the engine from overheating, as when pulling a trailer up a hill. If the condition occurs frequently, check the following for a possible cause

1. Check for inoperative engine cooling fans.
2. Check for debris in front of A/C condenser.
3. Check for missing or out of location radiator or A/C condenser air shields.
4. Check for low coolant level.
5. Check for inoperative thermostat.
6. Check for water pump failure.
7. Check PCM for current or history engine coolant temperature sensor DTCs. If any DTCs are set, repair as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .
8. Check for trailer weight exceeding 1000 lbs. (454 kg) in extreme high ambient temperatures.
9. Check for any aftermarket products affecting cooling system performance.

1. If air conditioning diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «AIR CONDITIONING DIAGNOSTIC SYSTEM CHECK»(ref-126121-S00049102342001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Ensure ignition is on. Wait at least one minute for the A/C system pressure to equalize. Using scan tool, check for current and history DTCs in DIM menu. If DTC P1540 is stored as current, go to next step. If DTC P1540 is not stored as current, see «DIAGNOSTIC AIDS»(ref-126121-S28109621442001102400000) .
3. Connect A/C service gauges to high and low pressure ports. Note A/C system pressure. Using scan tool, select DIM A/C information from data list and observe A/C pressure parameter. Note pressure reading. Compare scan tool reading with reading noted from A/C service gauges. If readings are within plus or minus 20 psi, check A/C system performance. See A/C SYSTEM PERFORMANCE under SYSTEM TESTS in AUTOMATIC A/C-HEATER SYSTEMS - AURORA article in AIR CONDITIONING & HEATING. If readings are not within plus or minus 20 psi, go to next step.
4. Replace A/C pressure sensor. Sensor is located in discharge hose of A/C compressor. After repairs, go to next step.
5. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
6. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

If DTC P1540 is stored as a history code it indicates that the DIM received a high A/C refrigerant pressure message from the PCM. This code could also be caused by an intermittent short to voltage on the A/C refrigerant pressure sensor signal circuit which would cause the PCM to set DTC P0530. DTC may also be the result of an actual A/C refrigerant over-pressure condition. It is possible for the refrigerant system pressure to exceed 430 psi (2968 kPa) during extended engine idle speed with A/C on when ambient temperatures are greater than 105°F (41°C). This could be caused by the following

1. Overcharged A/C system.
2. Failed A/C refrigerant pressure sensor.
3. Blockage in a refrigerant line.
4. Debris in front of the A/C condenser.
5. Radiator or A/C condenser air shields missing or out of location.
6. Inoperative engine cooling fans.
7. Extended periods at idle in city traffic followed by rapid acceleration.
8. Aftermarket products affecting cooling system performance.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Turn ignition on. Release brake pedal. Using scan tool, observe EXTENDED TRAVEL BRAKE parameter. If scan tool displays RELEASED, go to next step. If scan tool does not display RELEASED, go to step 6.
3. Depress brake pedal more than half-way down. If scan tool displays APPLIED, no problem is indicated at this time. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article. If scan tool does not display APPLIED, go to next step. NOTE: Brake switch consists of extended travel brake switch and TCC brake switch.
4. Disconnect brake switch connector. If scan tool displays APPLIED, go to step 10. If scan tool does not display APPLIED, go to next step.
5. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Using a test light connected to positive battery voltage, probe terminal No. 60 (Gray wire) at PCM C2 harness connector. see scheme 2 If test light illuminates, repair short to ground in Gray wire between PCM and brake switch. After repairs, go to step 13. If test light does not illuminate, go to step 11.
6. Connect a 3-amp fused jumper wire between Gray and Black/White wires at brake switch harness connector. Using scan tool, observe extended travel brake switch parameter. If scan tool displays RELEASED, go to next step. If scan tool does not display RELEASED, go to step 8.
7. Check for poor connections at brake switch connector. Repair connector as necessary. After repairs, go to step 13. If connector is okay, go to step 10.
8. Turn ignition off. Disconnect PCM connectors. PCM is located in engine compartment, inside air filter housing. Check continuity between ground and Black/White wire at brake switch harness connector. If continuity does not exist, repair open in Black/White wire between brake switch and ground connection. Ground connection is located at rear of engine, below engine coolant temperature sensor. If continuity exists, go to next step.
9. Check continuity of Gray wire between brake switch harness connector and terminal No. 60 at PCM C2 harness connector. see scheme 2 If continuity does not exist, repair open Gray wire. After repairs, go to step 13. If continuity exists, go to step 11.
10. Replace brake switch. After repairs, go to next step.
11. Check for poor connections at PCM connectors. Repair connector as necessary. After repairs, go to step 13. If connectors are okay, go to next step.
12. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
13. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
14. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Check PCM and engine grounds. Ensure grounds are clean and tight. See WIRING DIAGRAMS article. If any problems are found, repair as necessary. After repairs, go to step 10. If no problems are found, go to next step.
3. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000). If no other DTCs are set, go to next step.
4. Disconnect EGR valve. see scheme 6 Disconnect TP sensor and MAP sensor. Disconnect EOP sensor. EOP sensor is located near oil filter housing. Turn ignition on. Measure voltage between ground and 5-volt reference circuit (Gray wire) at any disconnected component harness connector. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, go to step 8.
5. Reconnect one disconnected component at a time while measuring voltage between ground and 5-volt reference circuit (Gray wire) at any disconnected component harness connector. If component being reconnected caused voltage to vary outside 4.5-5.5 volts, go to next step. If component being reconnected did not cause voltage to vary outside 4.5-5.5 volts, see «DIAGNOSTIC AIDS»(ref-126121-S14197329932001110700000).
6. Check for short to power or short to ground on all other circuits connected to affected component. See WIRING DIAGRAMS article. Repair wiring as necessary. After repairs, reconnect component and repeat previous step. If wiring is okay, go to next step.
7. Replace affected component. After repairs, go to step 10.
8. Turn ignition off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Check 5-reference circuit (Gray wire) for short to ground and short to power. Repair wiring as necessary. After repairs, go to step 10. If wiring is okay, go to next step.
9. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000). After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2.
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000).

Check PCM connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connections. Check for damaged wiring harness. If wiring harness appears to be okay, observe MAP sensor display on scan tool. With ignition on, wiggle connectors and wiring harnesses related to TP sensor, MAP sensor, EOP sensor and EGR valve. A change in MAP sensor display will indicate location of malfunction. Reviewing failure records vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to set occurs. This may assist in diagnosing the condition.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. Check PCM and engine grounds. Ensure grounds are clean and tight. See WIRING DIAGRAMS article. If any problems are found, repair as necessary. After repairs, go to step 10 . If no problems are found, go to next step.
3. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) . If no other DTCs are set, go to next step.
4. Disconnect A/C pressure sensor connector. Sensor is located in discharge hose of A/C compressor. Disconnect FTP sensor connector. FTP sensor is located on top of fuel tank and can be accessed through an inspection panel in trunk. Turn ignition on. Measure voltage between ground and 5-volt reference circuit (Gray wire) at either disconnected sensor harness connector. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, go to step 8 .
5. Reconnect one disconnected sensor at a time while measuring voltage between ground and 5-volt reference circuit (Gray wire) at other disconnected sensor harness connector. If sensor being reconnected caused voltage to vary outside 4.5-5.5 volts, go to next step. If sensor being reconnected did not cause voltage to vary outside 4.5-5.5 volts, see «DIAGNOSTIC AIDS»(ref-126121-S17798199632001110700000) .
6. Check for short to power or short to ground on all other circuits connected to affected sensor. See WIRING DIAGRAMS article. Repair wiring as necessary. After repairs, reconnect sensor and repeat previous step. If wiring is okay, go to next step.
7. Replace affected sensor. After repairs, go to step 10 .
8. Turn ignition off. Disconnect PCM harness connector. PCM is located in engine compartment, inside air filter housing. Turn ignition on. Check 5-reference circuit (Gray wire) for short to ground and short to power. Repair wiring as necessary. After repairs, go to step 10 . If wiring is okay, go to next step.
9. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . After repairs, go to next step.
10. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
11. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

Check PCM connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connections. Check for damaged wiring harness. If wiring harness appears to be okay, observe A/C pressure sensor display on scan tool. With ignition on, wiggle connectors and wiring harnesses related to FTP sensor and A/C pressure sensor. A change in A/C pressure sensor display will indicate location of malfunction. Reviewing failure records vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to set occurs. This may assist in diagnosing the condition.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0560 is set, diagnose charging system. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in GENERATORS & REGULATORS - AURORA article in STARTING & CHARGING SYSTEMS. If DTC P0560 is not set, go to next step.
3. Using scan tool, select OUTPUT DRIVER DATA list. Observe parameters on scan tool. If any parameters indicate a fault is present, go to next step. If no parameters indicate a fault is present, go to step 5 .
4. Check for a short to voltage on control circuit of component that indicated a fault. See WIRING DIAGRAMS article. Repair wiring as necessary. After repairs, go to step 6 . If wiring is okay, go to next step.
5. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . After repairs, go to next step.
6. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

An over charging condition may set this DTC. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in GENERATORS & REGULATORS - AURORA article in STARTING & CHARGING SYSTEMS.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0560 is set, diagnose charging system. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in GENERATORS & REGULATORS - AURORA article in STARTING & CHARGING SYSTEMS. If DTC P0560 is not set, go to next step.
3. Using scan tool, select OUTPUT DRIVER DATA list. Observe parameters on scan tool. If any parameters indicate a fault is present, go to next step. If no parameters indicate a fault is present, go to step 5 .
4. Check for a short to voltage on control circuit of component that indicated a fault. See WIRING DIAGRAMS article. Repair wiring as necessary. After repairs, go to step 6 . If wiring is okay, go to next step.
5. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . After repairs, go to next step.
6. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

An over charging condition may set this DTC. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in GENERATORS & REGULATORS - AURORA article in STARTING & CHARGING SYSTEMS.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0560 is set, diagnose charging system. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in GENERATORS & REGULATORS - AURORA article in STARTING & CHARGING SYSTEMS. If DTC P0560 is not set, go to next step.
3. Using scan tool, select OUTPUT DRIVER DATA list. Observe parameters on scan tool. If any parameters indicate a fault is present, go to next step. If no parameters indicate a fault is present, go to step 5 .
4. Check for a short to voltage on control circuit of component that indicated a fault. See WIRING DIAGRAMS article. Repair wiring as necessary. After repairs, go to step 6 . If wiring is okay, go to next step.
5. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . After repairs, go to next step.
6. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

An over charging condition may set this DTC. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in GENERATORS & REGULATORS - AURORA article in STARTING & CHARGING SYSTEMS.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to «POWERTRAIN DIAGNOSTIC SYSTEM CHECK»(ref-126121-S16975031962001102400000) under DIAGNOSTIC SYSTEM CHECKS.
2. If DTC P0560 is set, diagnose charging system. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in GENERATORS & REGULATORS - AURORA article in STARTING & CHARGING SYSTEMS. If DTC P0560 is not set, go to next step.
3. Using scan tool, select OUTPUT DRIVER DATA list. Observe parameters on scan tool. If any parameters indicate a fault is present, go to next step. If no parameters indicate a fault is present, go to step 5 .
4. Check for a short to voltage on control circuit of component that indicated a fault. See WIRING DIAGRAMS article. Repair wiring as necessary. After repairs, go to step 6 . If wiring is okay, go to next step.
5. Replace PCM. Program replacement PCM. See «PROGRAMMING»(ref-126121-S25122286972001102400000) . After repairs, go to next step.
6. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC as specified in code enable criteria. If DTC runs and passes, go to next step. If DTC resets, go to step 2 .
7. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, test is complete. If any other DTCs are set, repair DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-126121-S19628632112001102400000) .

An over charging condition may set this DTC. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in GENERATORS & REGULATORS - AURORA article in STARTING & CHARGING SYSTEMS.