Engine Controls - Self Diagnostics - 4.3L: Diagnosis Chevrolet Silverado 1500 HD

ON-BOARD DIAGNOSTICS

PCM is equipped with a self-diagnostic system which detects system failures or abnormalities. When a malfunction occurs, PCM will store a Diagnostic Trouble Code (DTC) and, in most cases, illuminate the Malfunction Indicator Light (MIL) located on instrument cluster.

There are 2 paths for accessing on-board diagnostics. It is necessary to access information through both paths, as each path presents some different information.

1. Generic OBD-II This provides all generic codes and some OEM codes, serial data PIDs required for generic OBD-II and some OEM PIDs, monitor status, pending codes and freeze frame.
2. OEM All DTCs, all PIDs, failure records, enhanced scan tool information and all other OEM scanner functions.

Scan Tool Snapshot

The scan tool can be set up to take a snapshot of the parameters available via serial data. The snapshot function records live data over a period of time. The recorded data can be played back and analyzed. The scan tool can also graph parameters singly or in combinations of parameters for comparison. The snapshot can be triggered manually at the time the symptom is noticed, or set up in advance to trigger when a DTC sets. An abnormal value captured in the recorded data may point to a system or component that needs to be investigated further. Refer to the scan tool user instructions for more information on the Snapshot function.

DIAGNOSTIC STARTING POINT - ENGINE CONTROLS

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. Diagnostic system check must be performed before using specific DTC testing procedure. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-158208-S20709970632003091700000) .
2. If no DTCs are present and a driveability problem exists, see «SYMPTOMS»(ref-152982-S33481225962003030700000) in TROUBLE SHOOTING - NO CODES - 4.3L SIERRA & SILVERADO article. Doing so will help identify proper system or component to check in «SYSTEM & COMPONENT TESTING - 4.3L SIERRA & SILVERADO»(ref-153194) article.
3. After necessary repairs are made, clear DTCs, verify vehicle will enter "closed loop" operation and ensure DTC does not reset.

Diagnostic Procedures

Note. Do not perform this diagnostic if there is not a driveability concern, unless another procedure directs you to this diagnostic. Before you proceed with diagnosis, search for applicable service bulletins. Unless a diagnostic procedure instructs you, do NOT clear the DTCs. If there is a condition with the starting system, see appropriate STARTERS article in ELECTRICAL. Ensure the battery has a full charge. Ensure the battery cables are clean and tight. Ensure the PCM grounds are clean, tight, and in the correct location.

1. Install a scan tool. Does the scan tool turn ON? If yes, go to next step. If no, see SCAN TOOL DOES NOT POWER UP in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
2. Turn ON the ignition, with the engine OFF. Attempt to establish communication with the listed control modules. If you are using a Tech 2(R), obtain the information using the Class 2 Message Monitor feature: PCM. Vehicle Theft Deterrent (VTD). Instrument Panel (IP) cluster. Electronic Brake Control Module (EBCM). Heating, Ventilation, and Air Conditioning (HVAC). Does the scan tool communicate with all the listed control modules? If yes, go to next step. If no, see SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Attempt to start the engine. Does the engine start and idle? If yes, go to next step. If no, see «SYMPTOMS»(ref-152982-S33481225962003030700000) in TROUBLE SHOOTING - NO CODES - 4.3L SIERRA & SILVERADO article.
4. Select the DTC display function for the following control modules: PCM, VTD, IP Cluster, EBCM, HVAC. Does the scan tool display any DTCs? If yes, go to next step. If no, go to step 9 .
5. With a scan tool, select Captured Info in order to store the powertrain DTC information. When complete, go to next step.
6. Does the scan tool display DTCs which begin with a "U"? If yes, see appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If no, go to next step.
7. Does the scan tool display DTC P0601, P0602, P0604, or P1683? If yes, see «DTC P0601-P0607, P1600, P1621, P1627, P1680, P1681 & P1683 & P2610: PCM MEMORY»(ref-158208-S11690446882003091700000) under DIAGNOSTIC TESTS. If no, go to next step.
8. Does the scan tool display DTC P0562, P0563, P1637 or P1638? If yes, see appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If no, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158208-S06912544392003091700000) .
9. Is the customer's concern with the automatic transmission? If yes, see appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS. If no, go to next step.
10. Is the customer's concern with Inspection and Maintenance (I/M) testing? If yes, see «INSPECTION/MAINTENANCE SYSTEM CHECK»(ref-158208-S07697983882003091700000) under DRIVE CYCLES.
11. Review the following symptoms. Hard start, surges/chugs, lack of power, sluggishness, sponginess, detonation/spark knock, hesitation, sag, stumble, cuts out, misses, poor fuel economy, poor fuel fill quality, rough, unstable, or incorrect idle and stalling, dieseling, run-on and backfire. See «TROUBLE SHOOTING - NO CODES - 4.3L SIERRA & SILVERADO»(ref-152982) article. Did you find and correct the condition? If yes, system is okay. If no, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) .

Diagnostic Procedure

1. The Diagnostic System Check will provide the following information: The identification of the control module(s) which command the system. The ability of the control module(s) to communicate through the serial data circuit. The identification of any stored Diagnostic Trouble Codes (DTCs) and their status. The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.
2. Install a scan tool. Does the scan tool turn ON? If yes, go to next step. If no, see SCAN TOOL DOES NOT POWER UP in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
3. Turn ON the ignition, with the engine OFF. Attempt to establish communication with the instrument cluster and PCM. Does the scan tool communicate with the instrument cluster and PCM? If yes, go to next step. If no, see SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
4. Select the Powertrain Control Module display DTCs function on the scan tool. Does the scan tool display any DTCs? If yes, go to next step. If no, see «COOLING SYSTEM TROUBLE SHOOTING»(ref-27342-S11025938142001112800000) under ENGINE MECHANICAL in TROUBLE SHOOTING - BASIC PROCEDURES article in GENERAL INFORMATION.
5. Does the scan tool display DTCs which begin with a "U"? If yes, see appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT for diagnosis. If no, go to next step.
6. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158208-S06912544392003091700000) .

RETRIEVING DIAGNOSTIC TROUBLE CODES

DTCs are retrieved using a Tech 2(R) scan tool, or other OBD-II compatible scan tool connected to OBD-II 16-pin Data Link Connector (DLC). See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS . DLC is located below left side of dash.

CLEARING DIAGNOSTIC TROUBLE CODES

There are 3 methods to clear DTCs.

Scan Tool

Scan tool is preferable way to clear DTC information. Freeze frame and failure record data will also be cleared. PCM adaptive learning and system monitors will only be cleared for those system which had a stored DTC.

SCAN TOOL USAGE

Scan tool is a specialized tester which, when connected to DLC, can be used to diagnose on-board computer control systems by providing instant access to circuit voltage information without need to crawl under dash or hood to backprobe sensors and connectors.

Scan tool reduces diagnostic time dramatically by furnishing input data (voltage signals) which can be compared to specification parameters. They may also furnish information on output device (solenoids and motors) status. However, status parameters only indicate output signals have been sent to devices by PCM; they do not indicate whether devices have responded properly to signal. Verify proper response at output device using a voltmeter or test light.

A problem may exist even if DTCs are not present. About 80 percent of driveability problems occur without setting DTCs. Sensors that are out of calibration will not set a DTC but will cause driveability problems.

Using a scan tool is the easiest method of checking sensor specifications and other data parameters. Scan tool is also useful in finding intermittent wiring problems by wiggling wiring harnesses and connections (key on, engine off) while observing data parameters.

Note. If erroneous voltage signals are suspected, verify tester information using a digital voltmeter and wiring schematic. If non-existent DTCs are displayed, DO NOT use scan tool for diagnosis. Contact tester manufacturer for additional information.

Scan Tool Display

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(R) scan tool. See scan tool operator's manual for additional information.

The following are Tech 2(R) scan tool sub-menus in the DTC INFO and SPECIFIC DTC modes

1. DTC INFO MODE Used to search for specific type of stored DTC information. There are 7 choices in this mode. Technician may be instructed to test DTCs in a certain manner. Follow the affected DTC test procedures. To get complete description of any status, hit ENTER key before pressing the desired "F" key.
2. DTC STATUS This selection will display any DTCs that have not run during the current ignition cycle or have reported a test failure during this ignition up to a maximum of 33 DTCs. A DTC test that runs and passes will cause affected DTC to be removed from scan tool screen.
3. FAIL THIS IGN. This selection will display all DTCs that have failed during the present ignition cycle.
4. HISTORY This selection will display only DTCs that are stored in the control module's history memory. It will not display type "D" DTCs. It 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.
5. LAST TEST FAIL This selection will only display DTCs that have 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.
6. MIL REQUEST This selection will only display DTCs that are requesting MIL illumination. Type "C" DTCs cannot be displayed using this option. This selection will report type "B" DTCs only after MIL illumination has been requested.
7. NOT RUN SCC Not Run Since Code Clear option will display up to 33 DTCs that have not run since DTCs were last cleared. Since any displayed DTCs have not run, their condition (passing or failing) is unknown.
8. TEST FAIL SCC Test Fail Since Code Clear selection will display all active and history DTCs that have reported a test failure since the last time DTCs were cleared. DTCs that last failed over 40 warm-up cycles before this option is selected will not be displayed.
9. FAILED SINCE CLEAR This message indicates the DTC has failed at least once within the last 40 warm-up cycles since the last time DTCs were cleared.
10. NOT RUN SINCE CL. Not Run Since Cleared message indicates that the selected diagnostic test has not run since the last time DTCs were cleared. Therefore, the diagnostic test status (passed or failed) is unknown. After DTCs are cleared, this message will continue to be displayed until the diagnostic test runs.
11. NOT RUN THIS IGN. Not Run This Ignition message indicates the selected diagnostic test has not run this ignition cycle.
12. TEST RAN AND PASSED This message indicates the selected diagnostic test has: Passed the last test. Ran and passed during this ignition cycle. Ran and passed since DTCs were last cleared. Test has not failed since DTCs were last cleared. If this message is displayed, repair is complete. If FAILED THIS IGN. message is displayed, repair is incomplete and further diagnosis is required.

Diagnostic Aids

The I/M System Status display provides an indication of when the control module has completed the required tests. This does not necessarily mean that the test has passed, only that a decision was made. If the diagnostic fails, a DTC will indicate the failure. If a failure indication is present for a DTC associated with one of the I/M regulated systems, the failure indication may prevent other required tests from running. For example, a DTC for the control circuit of the relay controlling an AIR pump may not be listed in the INSPECTION/MAINTENANCE SYSTEM DTCS table because this is a continuous test. If this DTC is set, the Active Tests for the AIR system may not run. The I/M System Status information may be useful for a technician to determine if diagnostics have run when verifying repairs.

Conditions for Running

Cold Start

1. The Barometric (BARO) pressure is more than 74 kPa.
2. The Engine Coolant Temperature (ECT) is below 86°F (30°C).
3. The Intake Air Temperature (IAT) is below 86°F (30°C).
4. The difference between the Intake Air Temperature (IAT) and the Engine Coolant Temperature (ECT) is 14°F (8°C) or less.
5. The battery voltage is between 9-18 volts.
6. The fuel level is between 1/4 and 3/4.

Rough road conditions may prevent some of the tests from running. Extreme high or low ambient temperatures may prevent tests such as Heated Oxygen Sensor (HO2S) Heater and evaporative emission (EVAP) System from initiating. If a step is interrupted before completion, perform the remaining portion of the set procedures. Any portion of the set procedure that requires the engine at operating temperature may be repeated. This allows most of the diagnostics to run and the remaining tests can be performed using the individual System Set Procedures. If the vehicle has recently run, start this procedure at step 3 . This will allow the tests that require the engine at operating temperature to run. Using this method allows shorter cool down periods if the tests requiring a cold start do not initiate. The scan tool can be used to monitor each of the I/M System Status indicators during the I/M Complete System Set Procedure. When all of the indicators for a test step have updated to YES, testing can move on to the next step even if the remaining portion of the test is not complete. For example, step 3 is designed to run the EVAP, secondary Air Injection (AIR), and HO2S tests. The procedure instructs the technician to operate the vehicle in the enable conditions for 6 minutes. If all 3 tests have updated to YES within 4 minutes, it is not necessary to continue with the enable conditions and testing can advance to the next step.

INSPECTION/MAINTENANCE SYSTEM DTCS

1. The Barometric (BARO) pressure is more than 74 kPa.
2. The engine coolant is at operating temperature, 160-248°F (71-120°C).
3. The Intake Air Temperature (IAT) is between 5-167°F (-15 to 75°C).
4. The engine is in Closed Loop fuel control.
5. The engine has run for 6-8 minutes off idle in order to initiate test.
6. The battery voltage is between 11-18 volts.

The control module 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 will update to YES. If a test for a specific system has failed, the I/M System Status will update 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 will indicate the Malfunction Indicator Lamp (MIL) is requested. The I/M System Status also registers the number of diagnostic trouble codes (DTCs). The first failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update the I/M System Status to YES. A second trip is required, and all the conditions to run must be met in order for the test to run again. These conditions may include a partial to complete engine cool down. The I/M System Status will update only when an emission related DTC fails the second time, or when all of the tests pass. If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning ON, may cause the test to abort. If a diagnostic test is difficult to run, observe the I/M System Status display while maintaining the necessary enable conditions until the system status updates to YES.

1. DTCs P0442, P0446, P0496 are not set.
2. The barometric pressure is more than 75 kPa.
3. The fuel level is between 1/4 and 3/4.
4. The battery voltage is between 10-18 volts.
5. The test will initiate only after a cold start. The control module considers the engine to be cold if the following conditions are met: The Engine Coolant Temperature (ECT) is between 39-86°F (3.8-30.0°C). The Intake Air Temperature (IAT) is between 39-86°F (3.8-30.0°C). The difference between the ECT and the IAT is less than 14°F (8°C).

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

1. The Engine Coolant Temperature (ECT) is more than 135°F (57°C).
2. The engine is running in Closed Loop fuel control.
3. The engine has been running for more than 160 seconds.
4. The battery voltage is between 9-18 volts.

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 will update to YES. If a test for a specific system has failed, the I/M System Status will update 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 will indicate the Malfunction Indicator Lamp (MIL) is requested. The I/M System Status also registers the number of diagnostic trouble codes (DTCs). The first failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update the I/M System Status to YES. A second trip is required, and all the conditions to run must be met in order for the test to run again. These conditions may include a partial to complete engine cool down. The I/M System Status will update only when an emission related DTC fails the second time, or when all of the tests pass. If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning ON, may cause the test to abort. If a diagnostic test is difficult to run, observe the I/M System Status display while maintaining the necessary enable conditions until the system status updates to YES.

1. The start-up Engine Coolant Temperature (ECT) is less than 122°F (50°C).
2. The start-up Intake Air Temperature (IAT) is less than 122°F (50°C).
3. The difference between the IAT and the ECT is less than 14°F (8°C).
4. The battery voltage is between 11-18 volts.

The HO2S Heater Tests will normally run within the 2 minutes allotted in the procedure. If there is an indeterminate condition, the test may take up to 8 minutes on some vehicles before a decision of pass or fail is made. If the test does not update within the allotted period of time, continue operation within the enable conditions until the test updates to YES. If the test does not update to YES, it may have failed or aborted due to the loss of enabling conditions. Extremely high ambient temperatures may prevent the HO2S Heater Test from initiating. 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 will update to YES. If a test for a specific system has failed, the I/M System Status will update 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 will indicate the Malfunction Indicator Lamp (MIL) is requested. The I/M System Status also registers the number of diagnostic trouble codes (DTCs). The first failure of a type "B" DTC does not constitute a final determination of pass or fail, and will not update the I/M System Status to YES. A second trip is required, and all the conditions to run must be met in order for the test to run again. These conditions may include a partial to complete engine cool down. The I/M System Status will update only when an emission related DTC fails the second time, or when all of the tests pass. If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning ON, may cause the test to abort. If a diagnostic test is difficult to run, observe the I/M System Status display while maintaining the necessary enable conditions until the system status updates to YES.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TROUBLE CODE INDEX

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1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-158208-S20709970632003091700000) under SELF-DIAGNOSTIC SYSTEM.
2. Verify whether the instrument cluster is operational. If the Instrument Panel (IP) is completely inoperative, see appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Command the MIL ON and OFF with a scan tool. Does the MIL turn ON and OFF when commanded with a scan tool? If yes, problem is intermittent. See «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
3. Inspect the fuse that supplies ignition voltage to the cluster. Is the fuse open? If yes, go to step 11 . If no, go to next step.
4. Turn OFF the ignition. Remove the fuse that supplies voltage to the cluster. Disconnect the Powertrain Control Module (PCM) harness connectors. See «COMPONENT LOCATIONS»(ref-158208-S14900325472003091700000) . Turn ON the ignition with the engine OFF. Measure the voltage from the MIL control circuit in the PCM harness connector to a good ground. Is the voltage less than .3 volt? If yes, go to next step. If no, go to step 11 .
5. Turn OFF the ignition. Install the fuse that supplies voltage to the cluster. Turn ON the ignition with the engine OFF. Connect a 3-amp fused jumper wire between the MIL control circuit in the PCM harness connector and a good ground. Is the MIL illuminated? If yes, go to step 9 . If no, go to next step.
6. Turn OFF the ignition. Remove the Instrument Panel Cluster (IPC). See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Turn ON the ignition. Probe the MIL battery positive voltage circuit at the IPC harness connector with a test lamp connected to a good ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step 12 .
7. Test the MIL control circuit for an open or high resistance between the PCM and the IPC and repair as necessary. Did you find and correct the condition? If yes, go to step 15 . If no, go to next step.
8. Inspect for poor connections at the harness connector of the IPC and repair as necessary. Did you find and correct the condition? If yes, go to step 15 . If no, go to step 13 .
9. Inspect for poor connections at the harness connector of the PCM and repair as necessary. Did you find and correct the condition? If yes, go to step 15 . If no, go to step 14 .
10. Repair the short to ground in the MIL battery positive voltage circuit. Replace the fuse. After repairs, go to step 15 .
11. Repair the short to voltage in the MIL control circuit. After repairs, go to step 15 .
12. Repair the open in the ignition voltage circuit. After repairs, go to step 15 .
13. Repair or replace the IPC. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs, go to step 15 .
14. Replace the PCM. See appropriate REMOVAL & INSTALLATION article. Reprogram PCM. See «POWERTRAIN CONTROL MODULE»(ref-158208-S25190896492003111900000) under PROGRAMMING. After repairs, go to next step.
15. Turn OFF the ignition for 30 seconds. Does the vehicle operate correctly, without any MIL illumination and without any stored DTCs? If yes, system is okay. If no, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158208-S06912544392003091700000) .

If the problem is intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-158208-S20709970632003091700000) under SELF-DIAGNOSTIC SYSTEM.
2. Turn OFF the ignition. Disconnect the PCM. See «COMPONENT LOCATIONS»(ref-158208-S14900325472003091700000) . Turn ON the ignition, with the engine OFF. Observe the MIL. Is the MIL illuminated? If yes, go to next step. If no, go to step 5 .
3. Remove the Instrument Panel Cluster (IPC). See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Test the MIL control circuit for a short to ground between the PCM and the IPC. Did you find and correct the condition? If yes, go to step 6 . If no, go to next step.
4. Repair or replace the IPC. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs, go to step 6 .
5. Replace the PCM. See appropriate REMOVAL & INSTALLATION article. Reprogram PCM. See «POWERTRAIN CONTROL MODULE»(ref-158208-S25190896492003111900000) under PROGRAMMING. After repairs, go to next step.
6. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 2 .

If the problem is intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

DIAGNOSTIC TESTS

Note. Before clearing DTCs, perform powertrain diagnostic system check. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. Record FREEZE FRAME and FAILURE RECORDS for reference during testing. Data will be erased when DTCs are cleared. If VCM is replaced, NEW VCM must be programmed using special manufacturer's equipment.

Conditions For Running DTC

The engine is running.

Conditions For Setting DTC

When the engine is running, the cam sensor pulse is not detected at the correct relative position to the crankshaft sensor pulse.

Action Taken When DTC Sets

1. The control module illuminates the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Conditions For Clearing MIL/DTC

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Check for the following items

1. A loose or missing distributor hold down bolt.
2. A loose CMP sensor causing a variance in the sensor signal.
3. An incorrectly installed distributor - one tooth off in either advance or retard positions.
4. A loose distributor rotor on the distributor shaft.
5. Excessive free play in the timing chain and gear assembly.

If the condition is intermittent, see

INTERMITTENT CONDITIONS

under SELF-DIAGNOSTIC SYSTEM.

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1. DTCs P0102, P0103, P0106, P0107, P0108, P0121, P0122, P0123, P0442, P0443, P0446, P0449, P0455, and P0496 are not set.
2. The engine is cranking or running.
3. The ignition 1 signal is between 11 volts and 18 volts.
4. The Throttle Position (TP) sensor angle is less than 95 percent.
5. The change in the TP sensor angle is less than 5 percent.
6. The MAP sensor is less than 80 kPa.
7. The change in the MAP sensor is less than 3 kPa.
8. The above conditions are met for 1.5 seconds.

The PCM detects that the actual MAF sensor frequency signal is not within a predetermined range of the calculated MAF value for more than 4.0 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Inspect for the following conditions

1. An incorrectly routed harness. Inspect the harness of the MAF sensor in order to verify that it is not routed too close to the following components: The secondary ignition wires or coils. Any solenoids. Any relays. Any motors.
2. A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration. Inspect for any vacuum leaks downstream of the MAF sensor.
3. Inspect for any contamination or debris on the sensing elements of the MAF sensor.
4. Inspect the sir induction system for any water intrusion. Any water that reaches the MAF sensor will skew the sensor and may cause this DTC to set.
5. A wide open throttle acceleration from a stop should cause the MAF sensor g/s display on the scan tool to increase rapidly. This increase should be from 7-12 g/s at idle to 150 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
6. Inspect for a skewed or stuck ECT sensor.
7. A high resistance of 15 ohms or more on the ignition 1 voltage circuit may cause this DTC to set. A high resistance may cause a driveability concern before this DTC sets.
8. Inspect for a skewed or stuck TP sensor.
9. The barometric pressure that is used in order to calculate the predicted mass air flow value is initially based on the MAP sensor at key ON. When the engine is running, the MAP sensor value is continually updated near wide open throttle. A skewed MAP sensor will cause the calculated mass air flow value to be inaccurate and may result in a no start condition. The value shown for the MAP sensor display varies with the altitude. With the ignition ON and the engine OFF, 103 kPa is the approximate value near sea level. This value will decrease by approximately 3 kPa for every 1000 feet (305 meters) of altitude.
10. A high resistance on the 5-volt circuit of the MAP sensor may cause this DTC to set.
11. A high resistance on the low reference circuit of the MAP sensor may cause this DTC to set.
12. If the condition is intermittent, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM.

Condition may be related to aftermarket accessories. If the condition is intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

1. The engine is running.
2. The engine speed is more than 400 RPM.
3. The ignition 1 signal is more than 8 volts.
4. The MAF sensor frequency is stable for more than 0.7 second.

The PCM detects that the MAF sensor frequency signal is less than 1200 Hz.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Inspect for the following conditions

1. An incorrectly routed harness. Inspect the harness of the MAF sensor in order to verify that it is not routed too close to the following components: The secondary ignition wires or coils. Any solenoids. Any relays. Any motors.
2. A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration. Inspect for any vacuum leaks downstream of the MAF sensor.
3. A wide open throttle acceleration from a stop should cause the MAF sensor g/s display on the scan tool to increase rapidly. This increase should be from 7-12 g/s at idle to 150 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
4. A resistance of 15 Ohms or more on the ground circuit or the ignition 1 circuit of the MAF sensor can cause this DTC to set.

Condition may be related to aftermarket accessories. If the condition is intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

1. The engine is running.
2. The engine speed is more than 400 RPM.
3. The ignition 1 signal is more than 8 volts.
4. The MAF sensor frequency is stable for more than 0.7 second.

The PCM detects that the MAF sensor frequency signal is more than 12,000 Hz.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Inspect the air induction system for any water intrusion. The water rapidly cools the hot sensing elements in the sensor causing a false indication of excessive air flow. Any water that reaches the MAF sensor will skew the sensor and may cause this DTC to set.
2. A poor connection in the ignition 1 voltage circuit of the MAF sensor may cause this DTC to set.

Condition may be related to aftermarket accessories. If the condition is intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

1. DTCs P0101, P0102, P0103, P0107, P0108, P0121, P0122, P0123, P0442, P0443, and P0446 are not set.
2. The engine is running.
3. The engine speed is between 400-5000 RPM.
4. The change in engine speed is less than 125 RPM.
5. The traction control is not active.
6. A change in idle air is less than 10 g/s.
7. A change in the Exhaust Gas Recirculation (EGR) position is less than 10 percent.
8. The A/C compressor clutch is steady.
9. The power steering load is stable.
10. The clutch switch state does not change.
11. The brake switch state does not change.
12. All conditions are stable for 1 second.

The actual MAP sensor signal is not within the predicted range for 1.5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. The ignition is ON.
2. DTCs P0121, P0122, or P0123 are not set.
3. The throttle angle is more than 0 percent when the engine speed is less than 800 RPM., or the throttle angle is more than 12.5 percent when the engine speed is more than 800 RPM.

MAP sensor voltage is less than 0.10 volt for more than 2 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. The engine has been running for a length of time that is determined by start-up coolant temperature. The length of time ranges from 5.5 minutes at less than -22°F (-30°C) to 10 seconds at more than 86°F (30°C).
2. DTCs P0121, P0122, or P0123 are not set.
3. The throttle angle is 0 percent when the engine speed is less than 1200 RPM., or the throttle angle is less than 12.5 percent when the engine speed is more than 1200 RPM.

MAP sensor voltage is more than 4.9 volts for more than 2 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0502, or P0503 are not set.
2. The engine run time is more than 45 seconds.
3. The Vehicle Speed Sensor (VSS) indicates that vehicle speed is more than 25 MPH.

The IAT is more than 262°F (128°C) for 5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Scheme 467

Scheme 468

1. DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0125, P0128, P0502, or P0503 are not set.
2. The engine run time is more than 120 seconds.
3. The Vehicle Speed Sensor (VSS) indicates that vehicle speed is less than 7 MPH.
4. The Engine Coolant Temperature (ECT) is more than 140°F (60°C).
5. The Mass Air Flow (MAF) is less than 15 g/s.

The PCM detects that the IAT Sensor parameter is less than -36° F (-38° C) for more than 5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Scheme 469

Scheme 470

1. The ignition is ON.
2. The IAT Sensor parameter is more than 59° F (15° C).
3. DTCs P0112, P0113, P0117, P0118, P0125, P0128, P0601, P0602, or P1683 are not set.
4. The vehicle has a minimum ignition OFF time of 10 hours.

If the PCM detects a temperature difference of more than 27°F (15°C) between the ECT and the IAT, the vehicle must be driven for 7 minutes over 15 MPH. If the IAT decreases more than 5° F (3° C) then a block heater is indicated and the test is aborted. If the IAT temperature does not decrease, a block heater was not detected and this DTC will set.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTC P0116 is designed to detect an ECT sensor that is skewed high.
2. An IAT sensor that is skewed could cause this DTC to set.
3. When checking the ECT sensor, the Temperature vs Resistance table should be used in order to determine if a skewed sensor is the problem. See «SENSOR TEMPERATURE VS. RESISTANCE»(ref-158208-S19287914062003101400000) .
4. An ECT sensor that is leaking coolant at the connector, can cause this DTC to set.

The engine run time is more than 10 seconds, or the engine run time is less than 10 seconds when Intake Air Temperature (IAT) is less than 122° F (50° C).

The PCM detects the ECT sensor temperature is more than 282°F (139°C) for more than 20 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) if a failure is detected during 2 consecutive key cycles.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Scheme 471

Scheme 472

The engine has been running more than 60 seconds, or less than 60 seconds when the Intake Air Temperature (IAT) is more than 32° F (0° C)..

The PCM detects that the ECT sensor parameter is less than -36° F (-38° C) for 20 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) if a failure is detected during 2 consecutive key cycles.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module writes the operating conditions to the Freeze Frame and updated the Failure Records.

Conditions For Clearing MIL or DTC

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Scheme 473

Scheme 474

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0122, P0123, P0506, or P0507 are not set.
2. The engine is running for more than 2 minutes.
3. The Engine Coolant Temperature (ECT) is more than 158°F (70°C).
4. The MAP is less than 43 kPa for a TP sensor skewed high test.
5. The MAP is more than 67 kPa for a TP sensor skewed low test.
6. The MAP is steady for 2 seconds or more.
7. The TP does not vary more than 1.5 percent for 2 seconds or more.

1. The PCM detects that the TP sensor voltage is more than a predicted value when the MAP is less than 43 kPa.
2. The TP sensor reading is less than a predicted value when the MAP is more than 67 kPa.
3. The above conditions are present for 1 second.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions For Clearing the MIL/DTC

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Scheme 475

Scheme 476

Scheme 477

The ignition is ON.

The PCM detects that the TP sensor signal voltage is less than 0.1 volt for more than 2 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. The ignition is ON.
2. DTCs P0641 and P0651 are not set.

1. The TP sensor signal voltage is more than 4.9 volts.
2. The above conditions are present for more than 1 second.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0500, P0502, P0503, P1111, P1112, P1114, or P1115 are not set.
2. The Intake Air Temperature (IAT) is between 19-131° F (-7-55° C).
3. The start-up Engine Coolant Temperature is between -33-83° F (-36-28.5° C).
4. The engine running is between 2-35 minutes.
5. The vehicle speed is more than 5 MPH for more than 0.5 mi.
6. The Mass Air Flow (MAF) average reading is between 15-75 g/s with the average more than 12 g/s.

The PCM detects that

1. The calibrated amount of engine run time has been met.
2. The calibrated amount of engine air flow has been met.
3. The Engine Coolant Temperature for Closed Loop of 93° F (34° C) has not been met.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0125, P0500, P0502, P0503, P1111, P1112, P1114, or P1115 are not set.
2. The start up engine coolant temperature is less than 169° F (76° C).
3. The Air Intake Temperature (IAT) is between 19-131° F (-7-55° C).
4. The engine is running more than 2 minutes and less than 35 minutes.
5. The vehicle speed is more than 5 MPH for more than 1.5 mi.
6. The Mass Air Flow (MAF) is between 15-75 g/s with the average more than 12 g/s.

The PCM detects that

1. The calibrated amount of engine run time has been met.
2. The calibrated amount of engine air flow has been met.
3. The calibrated minimum Engine Coolant Temperature of 178° F (81° C) has not been met.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Lean Test Enable

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455 or P496 are not set.
2. The loop status parameter is closed.
3. The ignition 1 signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining is more than 10 percent.
5. The TP Sensor parameter is between 3-70 percent.

Power Enrichment Test Enable

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455 or P0496 are not set.
2. The loop status parameter is closed.
3. The ignition 1 signal parameter is between 10-18 volts.
4. The Fuel Tank Level Remaining is more than 10 percent.
5. The Engine Run Time parameter is more than 30 seconds.
6. The Power Enrichment parameter is active for more than 2 seconds.

Lean Test

1. The PCM detects that the affected HO2S voltage parameter is less than 200 mV for 165 seconds.

Power Enrichment Test

1. The PCM detects that the affected HO2S voltage parameter is less than 400 mV for 10 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
3. The control module commands Open Loop.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Rich Test Enable

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455 or P0496 are not set.
2. The ignition 1 signal parameter is between 10-18 volts.
3. The Fuel Tank Level Remaining is more than 10 percent.
4. The loop status parameter is closed.
5. The Throttle Position (TP) Sensor parameter is between 3-70 percent.

Decel. Fuel Cut-Off Test Enable

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455 or P0496 are not set.
2. The ignition 1 signal parameter is between 10-18 volts.
3. The Fuel Tank Level Remaining is more than 10 percent.
4. The loop status parameter is closed.
5. The Engine Run Time parameter is more than 30 seconds.
6. The Decel. Fuel Cutoff parameter is active for more than 4 seconds.

Rich Test

1. The PCM detects that the affected HO2S voltage parameter is more than 900 mV for 165 seconds.

Decel Fuel Cut-Off Test

1. The PCM detects that the affected HO2S voltage parameter is more than 250 mV for 5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
3. The control module commands Open Loop.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0300, P0442, P0446, P0452, P0453, P0455, or P0496 are not set.
2. The Engine Coolant Temperature (ECT) sensor is more than 140° F (60° C).
3. The engine run time is more than 160 seconds.
4. The Mass Air Flow (MAF) sensor is between 18-55 g/s.
5. The engine speed is between 1300-3000 RPM.
6. The Throttle Position (TP) sensor is more than 5 percent.
7. The loop status is closed.
8. The ignition 1 signal is between 10-18 volts.
9. The Evaporative (EVAP) emissions purge solenoid command is more than 1 percent.
10. The above conditions are met for 100 seconds.
11. The Fuel Tank Level Remaining parameter is more than 10 percent.

The rich-to-lean and lean-to-rich average response time is more than a calibrated value.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455 or P0496 are not set.
2. The engine run time is more than 300 seconds.
3. The ignition 1 signal is between 10-18 volts.

The HO2S signal voltage is steady between 350-550 mV for 60 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
3. The control module commands Open Loop.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455, or P0496 are not set.
2. The Engine Coolant Temperature (ECT) sensor parameter is more than 122°F (50°C).
3. The ignition 1 signal is between 10-18 volts.
4. The MAF Sensor parameter is between 3-40 g/s.
5. The Engine Speed parameter is between 500-3000 RPM.
6. The Engine Run Time parameter is more than 120 seconds.

1. The PCM detects that the affected HO2S Heater current parameter is more than 2.5 amps or less than 0.25 amps.
2. The above condition is met for 10 seconds.

1. The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

1. The PCM turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Use a scan tool in order to clear the MIL and the DTC.

Lean Test Enable

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455 or P496 are not set.
2. The ignition 1 signal is between 10-18 volts.
3. The fuel tank level remaining is more than 10 percent.
4. The loop status is closed.
5. The TP Sensor parameter is between 3-70 percent.

Power Enrichment Test Enable

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455 or P496 are not set.
2. The ignition 1 signal is between 10-18 volts.
3. The fuel tank level remaining is more than 10 percent.
4. The loop status is closed.
5. The Engine Run Time parameter is more than 30 seconds.
6. The Power Enrichment parameter is active for more than 2 seconds.

Lean Test

1. The PCM detects that the affected HO2S voltage parameter is less than 80 mV for 200 seconds.

Power Enrichment Test

1. The PCM detects that the affected HO2S voltage parameter is less than 490 mV for 10 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Rich Test Enable

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455 or P0496 are not set.
2. The ignition 1 signal is between 10-18 volts.
3. The fuel tank level remaining is more than 10 percent.
4. The loop status is closed.
5. The TP Sensor parameter is between 3-70 percent.

Decel Fuel Cut-Off Test Enable

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0442, P0446, P0452, P0453, P0455 or P0496 are not set.
2. The ignition 1 signal is between 10-18 volts.
3. The fuel tank level remaining is more than 10 percent.
4. The loop status is closed.
5. The Engine Run Time parameter is more than 30 seconds.
6. The Decel. Fuel Cutoff is active for more than 4 seconds.

Rich Test

1. The PCM detects that the affected HO2S voltage parameter is more than 950 mV for 200 seconds.

Decel Fuel Cut-Off Test

1. The PCM detects that the affected HO2S voltage parameter is more than 250 mV for 5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0141, P0161, P0200, P0300, P0442, P0446, P0452, P0453, P0455, or P496 are not set.
2. The engine run time is more than 300 seconds.
3. The loop status is closed.
4. The ignition 1 signal is between 10-18 volts.

1. The PCM detects that the affected HO2S voltage parameter is between 410-490 mV for 150 seconds.
2. The Throttle Position (TP) changes more than 5 percent within 1 second, 6 times.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0101, P0103, P0108, P0135, P0137, P0141, P0200, P0300, P0410, P0420, P0430, P0440, P0442, P0443, P0446, P0449, P0506, P0507 or P1441 are not set.
2. The Engine Coolant Temperature (ECT) is between 167-239°F (75-115°C).
3. The Intake Air Temperature (IAT) is between 4-194°F (-20-90°C).
4. The Manifold Absolute Pressure (MAP) is between 26-90 kPa.
5. The vehicle speed is less than 85 MPH.
6. The engine speed is between 400-3000 RPM.
7. The Barometric (BARO) pressure is more than 74 kPa.
8. The Mass Air Flow (MAF) is between 5-90 g/s.
9. The fuel level is more than 10 percent.
10. The throttle position is less than 90 percent.

1. The average long term fuel trim cell value is above 23 percent.
2. All of the above conditions are present for 6 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. The system will go lean if an injector is not supplying enough fuel.
2. A lean condition could be present during high fuel demand.
3. Using a scan tool, review the Failure Records. If an intermittent condition is suspected, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM.

1. DTCs P0101, P0103, P0108, P0135, P0137, P0141, P0200, P0300, P0410, P0420, P0430, P0440, P0442, P0443, P0446, P0449, P0506, P0507 or P1441 are not set.
2. The Engine Coolant Temperature (ECT) is between 167-239°F (75-115°C).
3. The Intake Air Temperature (IAT) is between 4-194°F (-20 to 90°C).
4. The Manifold Absolute Pressure (MAP) is between 26- 90 kPa.
5. The vehicle speed is less than 85 MPH.
6. The engine speed is between 400-3,000 RPM.
7. The Barometric (BARO) pressure is more than 74 kPa .
8. The Mass Air Flow (MAF) is between 5-90 g/s.
9. The fuel level is more than 10 percent.
10. The Throttle Position (TP) is less than 90 percent.

1. The average long term fuel trim value is below -13 percent.
2. All of the above conditions are present for 40 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Fuel contamination, such as water and alcohol, will affect fuel trim.
2. A malfunctioning MAF sensor can cause a rich condition and set this DTC. See «DTC P0101: MASS AIR FLOW SENSOR PERFORMANCE»(ref-158208-S31079670762003091700000) .
3. Using a scan tool, review the Failure Records. If an intermittent condition is suspected, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM.

1. The engine is running.
2. The ignition voltage is between 6-18 volts.

1. The PCM detects an incorrect voltage on the fuel injector control circuit.
2. The condition exists for 5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Performing the Fuel Injector Coil test may help isolate an intermittent condition. See «SYSTEM & COMPONENT TESTING - 4.3L SIERRA & SILVERADO»(ref-153194) article.
2. For an intermittent condition, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM.

Scheme 478

Scheme 479

1. The engine speed is more than 400 RPM.
2. The ignition voltage is between 6-18 volts.

1. The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.
2. The above conditions are present for a minimum of 2.5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Use a scan tool in order to clear the MIL and the DTC.

Scheme 480

Scheme 481

1. DTCs P0016, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0125, P0128, P0315, P0335, P0336, P0341, P0502, P0503, P1114, P1115, or P1121 are not set.
2. Then engine speed is between 450-5000 RPM.
3. The ignition voltage is between 10-18 volts.
4. The Engine Coolant Temperature (ECT) is between 19-266° F (-7-130° C).
5. The fuel level is more than 10 percent.
6. The throttle angle is steady within 1 percent.
7. The Anti-Lock Brake System (ABS) and the Traction Control System (TCS) are not active.
8. The transmission is not changing gears.
9. The A/C clutch is not changing states.
10. The PCM is not in fuel shut-off or decel fuel cut-off mode.
11. The PCM is not receiving a rough road signal.

The PCM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed mandated standards.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Excessive vibration from sources other than the engine could cause DTC P0300 to set. The following are possible sources of vibration: Variable thickness brake rotors. Drive shaft not balanced. Worn or damaged accessory drive belt.
2. There may be more or less cylinders actually misfiring than indicated by the scan tool.
3. Spray water on the secondary ignition components using a spray bottle. Look and listen for arcing or misfiring.

1. DTCs P0335, P0336, P0341 or P1345 are not set.
2. The engine coolant temperature (ECT) is more than 149° F (65° C).

The CKP system variation values are not stored in the PCM memory.

1. The control module illuminates the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL/DTC with a scan tool.

The CKP system variation compensating values are stored in PCM memory after a learn procedure has been performed. If the actual CKP variation is not within the CKP system variation compensating value stored in the PCM memory, DTC P0300 may set.

The CKP system variation learn procedure is also required when the following service procedures have been performed, regardless of whether DTC P0315 is set.

1. An engine replacement.
2. A PCM replacement.
3. A harmonic balancer replacement.
4. Any engine repairs which disturb the CKP sensor relationship.

If the CKP system variation learn procedure cannot be performed successfully, inspect for the following conditions

1. Worn crankshaft main bearings.
2. A damaged reluctor wheel.
3. Excessive crankshaft runout.
4. A damaged crankshaft.
5. Interference in the signal circuit of the CKP sensor.
6. A coolant temperature that is not within the Conditions for Running the DTC.
7. The ignition switch is in the ON position until the battery has sufficient voltage.
8. A PCM power disconnect with the ignition ON may erase the stored value and set DTC P0315.
9. Any foreign material passing between the CKP sensor and the reluctor wheel.

Scheme 482

The engine run time is more than 10 seconds.

The PCM detects a malfunction in the KS diagnostic circuitry that will not allow proper diagnosis of the KS system.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. The knock sensor must be torqued correctly to 18 ft. lbs. (25 N.m).
2. The mounting between the sensor and the engine must be free of burrs, casting flash, and foreign material.
3. The knock sensor head must be clear of the hoses, the brackets, and the engine electrical wiring.

Scheme 483

1. DTCs P0116, P0117, P0118, P0122, P0123, or P0125 are not set.
2. The Engine Coolant Temperature (ECT) is more than 140°F (60°C).
3. The engine run time is more than 10 seconds.
4. The Manifold Absolute Pressure (MAP) is less than 44 kPa.
5. The engine speed is between 2000-3000 RPM.
6. The system voltage is more than 10 volts.

The knock signal is outside the assigned range or not present.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Inspect the KS for physical damage. A KS that is dropped or damaged may cause a DTC to set.
2. Inspect the KS for proper installation. A KS that is loose or over torqued may cause a DTC to set. The KS mounting surface must be free of burrs, casting flash, and foreign material.
3. For an intermittent condition, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM.

1. DTCs P0101, P0102, P0103, or P0341 are not set.
2. The camshaft position (CMP) sensor is incrementing.
3. The Mass Air Flow (MAF) is more than 3 g/s in the crank mode.
4. The MAF is more than 5 g/s in the running mode.

The PCM determines no signal from the CKP sensor for more than 3 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following conditions may cause this DTC to set

1. Poor connection or poor terminal tension at the sensor.
2. Crankshaft reluctor wheel damage or improper installation.
3. Excessive air gap between the CKP sensor and the reluctor wheel.
4. Foreign material passing between the sensor and the reluctor wheel.

Excess crankshaft end play causes the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in any one of the following

1. A no-start.
2. A start and stall.
3. Erratic performance.

For an intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

Note. The CKP system variation learn procedure must be performed anytime the relationship between the CKP sensor and the CKP reluctor wheel is changed. See CKP SYSTEM VARIATION LEARN PROCEDURE under PROGRAMMING.

Scheme 484

Scheme 485

The engine is cranking or running.

The PCM determines that the CKP sensor signal is out of range for less than 3 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following problems may cause this DTC to set

1. Crankshaft reluctor wheel damage or improper installation.
2. The sensor is coning in contact with the reluctor wheel.
3. If the crankshaft rotates backwards, this DTC sets. This condition is only with vehicles equipped with a manual transmission. This condition can occur when a vehicle is on an incline and the clutch is released and an engine stall occurs.

Excess crankshaft end play will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in any one of the following conditions

1. A no-start.
2. A start and stall.
3. Erratic performance.

An improperly installed crankshaft could cause excess crankshaft end play.

For an intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

Note. The CKP system variation learn procedure must be performed anytime the relationship between the CKP sensor and the CKP reluctor wheel is changed. See CKP SYSTEM VARIATION LEARN PROCEDURE under PROGRAMMING.

Scheme 486

The engine is running.

The CMP sensor reference pulse is not detected once every 2 crankshaft revolutions.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) if a failure is detected during 2 consecutive key cycles.
2. The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame/Failure Records.

1. The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
2. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 40°F (22°C) from the start-up coolant temperature and the engine coolant reaches a temperature that is more than 158°F (70°C) during the same ignition cycle.
3. Use a scan tool in order to clear the DTCs.

1. Electromagnetic interference (EMI) from the ignition coil or from the spark plug wires could cause a faulty signal condition in the CMP signal circuit to the PCM. Ensure that the routing of the CMP circuitry is correct.
2. If the condition is intermittent, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM.

The engine is cranking.

The ignition control voltage is not 0.04-4.9 volts.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) the first time the diagnostic runs and fails.
2. The control module will set the DTC and records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.

1. The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
2. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 40°F (22°C) from the start-up coolant temperature and the engine coolant reaches a temperature that is more than 158°F (70°C) during the same ignition cycle.
3. Use a scan tool in order to clear the DTCs.

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0171, P0172, P0174, P0175, P0200, P0300, P0325, P0327, P0335, P0336, P0341, P0442, P0443, P0446, P0452, P0453, P0455, P0502, P0503, P0506, P0507, P1133, P1134, or P1153 are not set.
2. The intake air temperature (IAT) is between 5-185° F (-15-85° C).
3. The Barometric pressure (BARO) is more than 10.7 psi.
4. The engine is operating.
5. The Engine Coolant Temperature (ECT) is more than 158-248° F (70-120° C).
6. Since the end of the last idle period, the engine speed is more than 900 RPM for 40 seconds for manual transmissions, or 45 seconds for automatic transmissions.
7. The Closed Loop fuel control is enabled.

The PCM determines that the oxygen storage capability of the TWC has degraded to less than a calibrated threshold.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails.
3. The control module stores this information in the Freeze Frame/Failure Records. The PCM disables the EGR valve for the ignition cycle.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0125, P0335, P0336, P0341, P0342, P0351, P0443, P0446, P0449, P0452, P0453, P0455, P0496, P0500, P0502, P0503, P1106, P1107, or P1683 are not set.
2. The diagnostic runs once with a 10 hour minimum between tests after a fail.
3. DTC P0455 must run and pass.
4. The start up Intake Air Temperature (IAT) is between 39-86° F (4-30° C).
5. The start up Engine Coolant Temperature (ECT) is 86° F (30° C).
6. The start up IAT and ECT are within 15° F (8° C).
7. The barometric pressure (BARO) is more than 75 kPa.
8. The ambient air temperature is between 36-90° F (2-32° C).
9. The engine run time minimum is 600 seconds.
10. The odometer displays more than 10 miles.
11. The vehicle has traveled more than 3 miles this trip.
12. The ECT is more than 158° F (70° C).
13. The fuel level is between 15-85 percent.
14. The ignition is OFF.

The control module detects a pressure change that is less than a calibrated amount.

1. The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test ran and failed.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stored this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. The history DTC will clear after the PCM runs and passes 40 consecutive warm up cycles with no failure.
4. The DTC can be cleared by using a scan tool.

1. To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light.
2. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J41413-SPT.
3. For intermittent conditions, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM.

1. The engine speed is more than 400 RPM.
2. The system voltage is between 6-18 volts.

1. The control module detects that the commanded state of the driver and the actual state of the control circuit do not match.
2. The above conditions are present for a minimum of 5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTCs P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0147, P0151, P0152, P0153, P0154, P0155, P0157, P0158, P0160, P0161, P0167, P0220, P0442, P0443, P0449, P0452, P0453, P0455, P0502, P0503, P1111, P1112, P1114, P1115, or P1120, are not set.
2. The ignition voltage is between 10-18 volts.
3. The Barometric (BARO) pressure is more than 75 kPa.
4. The fuel level is between 15-85 percent.
5. The Engine Coolant Temperature (ECT) is between 39-86°F (4-30°C).
6. The Intake Air Temperature (IAT) is between 39-86°F (4-30°C).
7. The start up ECT and IAT are within 16°F (9°C) of each other.

1. The Fuel Tank Pressure (FTP) is less than -10 in. H2O.
2. The condition is present for at least 30 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. An intermittent condition could be caused by a damaged Evaporative Emission (EVAP) vent housing, a temporary blockage at the EVAP vent solenoid inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.
2. For intermittent conditions, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM.

1. The engine speed is more than 400 RPM.
2. The system voltage is between 6-18 volts.

1. The control module detects that the commanded state of the driver and the actual state of the control circuit do not match.
2. The above conditions are present for a minimum of 5 seconds.

1. The control module will illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test ran and failed.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes and updates the Failure Records.

1. The control module will turn OFF the MIL during the third consecutive trip in which the diagnostic ran and passed.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. The History DTC will clear after 40 consecutive warm-up cycles without a malfunction.
4. The DTC can be cleared with a scan tool.

The engine is running.

1. The fuel tank pressure sensor voltage is less than 0.1 volt.
2. All conditions are present for greater than 5 seconds.

Action Taken When the DTC Sets

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The engine is running.

1. The fuel tank pressure sensor voltage is more than 4.9 volts.
2. All conditions are present for greater than 5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. DTC P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0147, P0151, P0152, P0153, P0154, P0155, P0157, P0158, P0160, P0161, P0167, P0220, P0442, P0443, P0449, P0452, P0453, P0455, P0502, P0503, P1111, P1112, P1114, P1115, or P1120 are not set.
2. The engine is running.
3. The ignition voltage is between 10-18 volts.
4. The Barometric Pressure (BARO) is more than 75 kPa.
5. The fuel level is between 15-85 percent.
6. The Engine Coolant Temperature (ECT) is between 39-149° F (4-65° C).
7. The start up ECT and IAT are within 16° F (9° C) of each other.

The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control nodule writes the operating conditions to the Freeze Frame Records.

1. The PCM turns OFF the MIL after 3 consecutive ignition cycles in which the diagnostic test runs and passes.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. A Scan Tool can clear the MIL/DTC.

1. To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. Introducing smoke in 15 second intervals will allow less pressure into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
2. A temporary blockage in the EVAP purge solenoid, purge pipe or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.
3. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the H 41413-SPT.
4. Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
5. For intermittent conditions, see «INTERMITTENT CONDITIONS»(ref-158208-S39553683022003091700000) under SELF-DIAGNOSTIC SYSTEM.

1. DTC P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0147, P0151, P0152, P0153, P0154, P0155, P0157, [0158, P0160, P0161, P0167, P0220, P0442, P0443, P0449, P0452, P0453, P0455, P0502, P0503, P1111, P1112, P1114, P1115, P1120 are not set.
2. The ignition voltage is between 10-18 volts.
3. The Barometric Pressure (BARO) is more than 75 kPa.
4. The fuel level is between 15-85 percent.
5. The Engine Coolant Temperature (ECT) is between 39-86° F (4-30° C).
6. The Intake Air Temperature (IAT) is between 39-86° F (4-30° C).
7. The start up ECT and IAT are within 16° F (9° C) of each other.

1. A continuous open purge flow condition is detected during the diagnostic test.
2. The fuel tank pressure decreases to less than -11 inches HO2.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL/DTC with a scan tool.

Scheme 487

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0171, P0172, P0174, P0175, P0200, P0300, P0442, P0443, P0446, P0449, P0455, PO496, P1111, P1112, P1114, P1115, P1121, P1122, P1380, and P1381 are not set.
2. The Engine Coolant Temperature (ECT) sensor is between 140-241°F (60-116°C).
3. The Barometric (BARO) pressure sensor is more than 65 kPa.
4. The engine run time is more than 60 seconds.
5. The Throttle Position (TP) sensor angle is less than 0.7 percent.
6. The Vehicle Speed Sensor (VSS) is less than 1 MPH.
7. The ignition voltage is between 9-18 volts.
8. The Intake Air Temperature (IAT) sensor is more than 14°F (-10°C).
9. The above conditions are met for 2 seconds.

The actual engine speed is 100 RPM less than the desired engine speed for more than 5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Inspect for the following conditions

1. High resistance in an IAC circuit.
2. Restricted air intake system.
3. Proper operation and installation of all air intake components.
4. Collapsed, clogged, or loose air intake ducts.
5. A clogged air filter.
6. Proper operation of the Mass Air Flow (MAF) sensor, if equipped.
7. A tampered with or damaged throttle stop screw.
8. A tampered with or damaged throttle plate, throttle shaft, or throttle linkage.
9. Objects blocking the IAC passage or throttle bore.
10. Excessive deposits in the IAC passage or on the IAC pintle.
11. Excessive deposits in the throttle bore or on the throttle plate.
12. Vacuum leaks.
13. A low or unstable idle condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve.

If the problem is determined to be intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0171, P0172, P0174, P0175, P0200, P0300, P0442, P0443, P0446, P0449, P0455, P0496, P1111, P1112, P1114, P1115, P1121, P1122, P1380, and P1381 are not set.
2. The Engine Coolant Temperature (ECT) sensor is between 140-241°F (60-116°C).
3. The Barometric (BARO) pressure sensor is more than 65 kPa.
4. The engine run time is more than 60 seconds.
5. The Throttle Position (TP) sensor angle is less than 0.7 percent.
6. The Vehicle Speed Sensor (VSS) is less than 1 MPH.
7. The ignition voltage is between 9-18 volts.
8. The Intake Air Temperature (IAT) sensor is more than 14°F (-10°C).
9. The above conditions are met for 2 seconds.

The actual engine speed is 200 RPM more than the desired engine speed for more than 5 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Inspect for the following conditions

1. High resistance in an IAC circuit.
2. The correct positive crankcase ventilation (PCV) valve, properly installed and proper operation of the PCV valve.
3. Proper operation and installation of all air intake components.
4. Proper installation and operation of the Mass Air Flow (MAF) sensor, if equipped.
5. A tampered with or damaged throttle stop screw.
6. A tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage, if equipped.
7. A skewed high TP sensor.
8. Excessive deposits in the IAC passage or on the IAC pintle.
9. Excessive deposits in the throttle bore or on the throttle plate.
10. Vacuum leaks.
11. A high or unstable idle condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve.

If the problem is determined to be intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

The engine is running.

1. The PCM detects a voltage out of tolerance condition on the 5-volt reference circuit.
2. The above condition is met for more than 10 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Scheme 488

Scheme 489

The engine is running.

1. The control module detects that the commanded state of the MIL driver and the actual state of the control circuit do not match.
2. The conditions are present for a minimum of 30 seconds.

The control module records the operating conditions at the time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. A current DTC, last test failed, clears when the diagnostic runs and does not fail.
2. A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Use a scan tool in order to clear the DTC.

The engine is running.

1. The PCM detects a voltage out of tolerance condition on the 5-volt reference circuit.
2. The above condition is present for longer than 2 seconds.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Scheme 490

Scheme 491

1. The engine has been running for a length of time that is determined by start-up coolant temperature. The length of time ranges from 5.5 minutes at less than -22° F (-30° C) to 10 seconds at more than 86° F (30° C).
2. DTC P0121, P0122, P0123 are not set.
3. The throttle angle is less than one percent when the engine speed is less than 1200 RPM.
4. The throttle angle is more than 12.5 percent when the engine speed is more than 1200 RPM.

The PCM detects that the MAP sensor voltage is intermittently more than 4.9 volts.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

Conditions For Clearing DTC

1. A current DTC, Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. The ignition is ON.
2. DTC P0121, P0122, P0123 are not set.
3. The throttle angle is more than 0 percent when the engine speed is less than 800 RPM.
4. The throttle angle is more than 12.5 percent when the engine speed is more than 800 RPM.

The PCM detects that the MAP sensor voltage is intermittently less than 0.10 volt.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC, Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0125, P0128, P0502, P0503, P1114 and P1115 are not set.
2. The engine run time is more than 120 seconds.
3. The engine coolant temperature is more than 140°F (60°C).
4. The vehicle speed is less than 7 MPH.
5. The mass air flow is less than 15 g/s.

The intake air temperature is less than -36° F (-38° C) for more than 1 second.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the MIL and the DTC with a scan tool.

Scheme 492

1. DTCs P0500, P0502, and P0503 are not set.
2. The engine run time is more than 45 seconds.
3. The vehicle speed is more than 25 MPH.

The IAT is more than 262°F (128°C) for more than 16 minutes.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the MIL and the DTC with a scan tool.

Scheme 493

Engine run time is more than 10 seconds.

The PCM detects that the ECT sensor parameter is more than 282° F (139° C) for more than 16 minutes.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

Scheme 494

Engine run time is more than 60 seconds.

The PCM detects that the ECT sensor parameter is less than -36° F (-38° C) for more than 16 minutes.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

Scheme 495

1. The ignition is ON.
2. DTCs P0641 and P0651 are not set.

The PCM detects that the TP sensor voltage is intermittently more than 4.9 volts.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. The ignition is ON.
2. DTCs P0641 and P0651 are not set.

The PCM detects that the TP sensor voltage is intermittently less than 0.15 volts.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

1. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0300, P0442, P0446, P0452, P0453, P0455, or P0496 are not set.
2. The engine run time is more than 160 seconds.
3. The engine speed is between 1200-3000 RPM.
4. The Engine Coolant Temperature (ECT) sensor is more than 140°F (60°C).
5. The mass air low (MAF) sensor is between 18-55 g/s.
6. The loop status is Closed.
7. The Throttle Position (TP) sensor is more than 5 percent.
8. The fuel tank level remaining is more than 10 percent.
9. The ignition 1 signal voltage is between 10-18 volts.
10. The Evaporative (EVAP) emissions purge solenoid command is more than 1 percent.
11. The above conditions are met for 100 seconds.

The HO2S lean to rich and rich to lean switches are less than a calibrated value.

1. The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC Last Test Failed clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
4. Clear the DTC with a scan tool.

1. DTCs P0117, P0118, P1114, and P1115 are not active.
2. The engine is running.

The engine coolant temperature is above 270°F (132°C) for 10 seconds or more.

1. The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the first trip in which the diagnostic test has been run and failed.
2. The PCM will signal the IPC to turn ON the Service Engine Soon indicator.
3. The PCM will alternately disable two groups of four cylinders by turning OFF the fuel injectors.
4. The PCM will store conditions which were present when the DTC set as Freeze Frame and File Records data.

1. The PCM will turn the MIL OFF after 3 consecutive trips that the diagnostic has been run and passed.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using the scan tool Clear DTC Information function.

Scheme 496

1. DTCs P0101, P0102, P0103, P0121, P0122, P0123, P0335, P0336, or P0742 are not set.
2. The vehicle speed is more than 10 MPH.
3. The engine load is less than 60 percent.
4. The engine misfire is detected and DTC P0300 set.
5. The engine speed is less than 3200 RPM.

An ABS malfunction exists preventing the PCM from receiving rough road detection data.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

Scheme 497

1. The engine load is less than 60 percent.
2. The engine speed is less than 3200 RPM.
3. The vehicle speed is more than 10 MPH.
4. Engine misfire is detected and DTC P0300 is set.

1. A serial data malfunction exists preventing the PCM from receiving rough road detection data.
2. The above conditions are met for 20 seconds.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The Malfunction Indicator Lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.