Engine Controls Self-Diagnostics - 3.4L: Diagnosis Chevrolet Venture I

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 1 or Tech 2 scan tool. See scan tool operator's manual for additional information.

The following are Tech 1 or Tech 2 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 IGNITION message is displayed, repair is incomplete and further diagnosis is required.

DIAGNOSTIC PROCEDURE

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

1. Ensure all engine systems not related to computer system are operating properly. DO NOT proceed with testing unless all other problems have been repaired. On-Board Diagnostic (OBD) system check must be performed before using specific DTC testing procedure. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) .
2. If DTCs were displayed, determine whether codes are hard or intermittent. Hard codes will cause MIL to illuminate continuously while engine is running. See «HARD OR INTERMITTENT TROUBLE CODE DETERMINATION»(ref-9296-S35860837122000101600000) . For diagnosing hard codes, proceed to appropriate DTC test. See «DIAGNOSTIC TESTS»(ref-9296-S34742973992000101600000) . For diagnosing intermittent codes, see appropriate TROUBLE SHOOTING - NO CODES article.
3. If no DTCs are present and a driveability problem exists, refer to SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article. Doing so will help identify proper system or component to check in appropriate SYSTEM & COMPONENT TESTING article.
4. After necessary repairs are made, clear DTCs, verify vehicle will enter "closed loop" operation and ensure DTC does not reset.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Diagnostic Trouble Codes (DTCs) are retrieved using a Tech 1 or 2 scan tool, or other OBD-II compatible scan tool connected to OBD-II 16-pin Data Link Connector (DLC). (Scheme 1) DLC is located below left side of dash.

Scheme 1

ON-BOARD DIAGNOSTIC SYSTEM CHECK

Note. Tech 1 or Tech 2 scan tool is required to perform OBD system check.

The OBD system check determines

1. If Malfunction Indicator Light (MIL) operates.
2. If PCM is operating and can recognize a fault.
3. If any DTCs are stored.

After performing procedures in PRELIMINARY INSPECTION & ADJUSTMENTS, BASIC FUEL SYSTEM CHECKS and BASIC IGNITION SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article, this is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in the OBD system check, if no codes are indicated and driveability problems still exist, see appropriate TROUBLE SHOOTING - NO CODES article and SCAN TOOL USAGE .

Note. Check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT perform the following procedure if driveability conditions are not present. DO NOT turn ignition off during the following procedure or clear DTCs unless instructed to do so.

1. Turn ignition on, with engine off. Observe MIL. If MIL illuminates, go to next step. If MIL does not illuminate, go to «MALFUNCTION INDICATOR LIGHT INOPERATIVE»(ref-9296-S38014063992000101600000) .
2. Turn ignition off. Connect scan tool. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «DATA LINK CONNECTOR DIAGNOSIS OR NO SCAN TOOL DATA»(ref-9296-S25445473552000101600000) .
3. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
4. Using scan tool, display LAST TEST FAIL information. If any DTCs are stored, save Freeze Frame and Failure Records information using scan tool CAPTURE INFO feature. If DTCs are indicated as last test failed, diagnose DTCs. See «DIAGNOSTIC TESTS»(ref-9296-S34742973992000101600000) . If DTCs are not indicated, go to next step.
5. Using scan tool, display DTC FAILURE RECORDS information. If DTC failure records are stored, save FREEZE FRAME and FAILURE RECORDS information using scan tool CAPTURE INFO feature. If failure records are stored, diagnose DTCs. See «DIAGNOSTIC TESTS»(ref-9296-S34742973992000101600000) . If failure records are not stored, go to next step.
6. Compare PCM data values displayed on scan tool to typical engine scan data values. If values are within limits, system is okay. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article.

DATA LINK CONNECTOR DIAGNOSIS OR NO SCAN TOOL DATA

Note. Perform On-Board Diagnostic (OBD) system check after completing any repairs. See ON-BOARD DIAGNOSTIC SYSTEM CHECK .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Connect a test light between Data Link Connector (DLC) battery feed circuit and ground circuit. See «WIRING DIAGRAMS»(ref-5022) article. If test light illuminates, go to step 4 . If test light does not illuminate, go to next step.
3. Using a test light connected to ground, probe DLC battery feed circuit. See «WIRING DIAGRAMS»(ref-5022) article. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 10 .
4. Turn ignition on, with engine off. Using DVOM connected to ground, probe class 2 serial data circuit at DLC. See «WIRING DIAGRAMS»(ref-5022) article. DVOM should read zero volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 7 .
5. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on, with engine off. Using DVOM connected to battery positive, probe class 2 serial data circuit at DLC. See «WIRING DIAGRAMS»(ref-5022) article. DVOM should read zero volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8 .
6. Check for open in class 2 serial data circuit between DLC and PCM. Repair as necessary. If circuit is okay, go to step 11 .
7. Check for short to voltage in class 2 serial data circuit. Repair as necessary. If circuit is okay, go to step 11 .
8. Locate and repair short to ground in class 2 serial data circuit.
9. Locate and repair open in DLC ground circuits.
10. Locate and repair open or short to ground in DLC battery feed circuit.
11. Replace PCM. Perform PCM relearn procedures.

DIAGNOSTIC TROUBLE CODE DEFINITION

Note. Use of Tech 1 or Tech 2 scan tool is required to retrieve DTCs. Refer to user reference manual supplied with scan tool.

DIAGNOSTIC TROUBLE CODE DEFINITION

HARD OR INTERMITTENT TROUBLE CODE DETERMINATION

During any diagnostic procedure, determine if DTC(s) are hard failure codes or intermittent failure codes. Diagnostic procedures will not always help analyze intermittent codes. To determine hard codes and intermittent codes

1. Enter diagnostic mode. Read and record all stored DTCs. Exit diagnostic mode and clear DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-9296-S23124260152000101600000) .
2. Apply parking brake and place transmission in Neutral or Park. Block drive wheels and start engine. MIL should turn off. Allow engine to reach normal operating temperature and continue to run for 2 minutes and note MIL.
3. If MIL illuminates, enter diagnostic mode. Read and record DTCs. This will reveal hard failure codes. Oxygen sensor related DTCs may require a road test to reset hard failures after DTCs were cleared.
4. If MIL does not illuminate, all stored DTCs were intermittent failures.

Note. DTCs will be recorded at various operating times. Some DTCs require operation of that sensor or switch for 5 seconds; others require operation for 5 minutes or longer at normal operating temperature, vehicle speed and load. Therefore, some DTCs may not set in a service bay operational mode and may require road testing vehicle in order to duplicate conditions under which code will set.

CLEARING DIAGNOSTIC TROUBLE CODES

To clear Diagnostic Trouble Codes (DTCs) from memory, use scan tool, following scan tool manufacturer's instructions. Codes may also be cleared by disconnecting power supply to PCM for at least 30 seconds.

Diagnostic Aids

Diagnostic aids are additional tips used to help diagnose trouble codes when inspected circuit is okay. Diagnostic aids may help lead to a definitive solution to trouble code problem.

SPECIAL TOOLS (DIAGNOSTIC)

Note. For scan data values, refer to scan tool manufacturer owner's manual or compare values with a known-good component or vehicle.

Note. A scan tool connected to DLC is used to read DTCs and check voltages in system on serial data line. A scan tool is required to retrieve vehicle information.

Computerized engine control system is most easily diagnosed using scan tool; however, other tools may aid in diagnosing problems. These tools are a tachometer, test light, ohmmeter, digital voltmeter with a 10-megohm input impedance (minimum), vacuum pump, vacuum gauge, fuel injector test light, and jumper wires with appropriate terminal ends and length. A test light, rather than a voltmeter, must be used when indicated by a diagnostic test. In addition, special jumper harnesses or testers may be required by manufacturer to facilitate diagnosis.

SCAN TOOL USAGE

Note. Before connecting scan tool to vehicle, diagnostic system should be checked to determine if system is operating properly and if information received will be accurate. See ON-BOARD DIAGNOSTIC SYSTEM CHECK . If vehicle does not pass OBD system check, information received may be invalid.

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 codes are displayed, DO NOT use scan tool for diagnosis. Contact tester manufacturer for additional information.

DIAGNOSTIC TESTS

Note. Before clearing DTCs, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK . Record FREEZE FRAME and FAILURE RECORDS for reference during testing. Data will be erased when DTCs are cleared.

Note. If PCM is replaced, replacement PCM must be programmed using required or special equipment.

Note. For component locations and PCM connector terminal identification, see appropriate SYSTEM & COMPONENT TESTING article.

Diagnostic Procedures

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Using scan tool, check for DTCs. If other DTCs are present, diagnose affected DTCs first. If no other DTCs are present, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Select SPECIFIC DTC function. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S17093122832000101600000) .
4. DO NOT clear DTCs. Disconnect MAF sensor connector. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and then stalls, go to step 6 .
5. Turn ignition off. Reconnect MAF sensor. Start engine. Monitor MAF signal on scan tool. Slowly increase engine speed to 3000 RPM. If MAF sensor signal increases with engine RPM, go to step 7 . If MAF sensor signal does not increase with engine RPM, go to next step.
6. Diagnose MAP sensor circuit. See ENGINE SENSORS & SWITCHES in appropriate SYSTEM & COMPONENT TESTING article. After repairs, go to step 20 .
7. Turn ignition on. Ensure throttle is closed. Using scan tool, observe throttle angle parameter. If scan tool indicates zero percent, go to next step. If scan tool does not indicate zero percent, diagnose using DTC P0121. Go to «DTC P0121: THROTTLE POSITION SENSOR PERFORMANCE»(ref-9296-S20681691422000101600000) .
8. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, with engine off. Using DVOM, check voltage between ground and signal circuit at MAF sensor harness connector. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 10 .
9. Connect test light between ignition feed circuit and ground circuit terminals at MAF sensor harness connector. If test light illuminates, go to step 13 . If test light does not illuminate, go to step 12 .
10. If voltage reading is less than 4.5 volts, go to step 14 . If voltage reading is not less than 4.5 volts, go to next step.
11. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on, with engine off. Using DVOM, check voltage between ground and signal circuit terminal at MAF sensor harness connector. If voltage reading is about zero volts, go to step 20 . If voltage reading is not about zero volts, go to step 17 .
12. Using a test light connected to ground, probe ignition feed circuit terminal at MAF sensor harness connector. If test light illuminates, go to step 15 . If test light does not illuminate, go to step 16 .
13. Check for poor connection at MAF sensor connector. Repair as necessary. After repairs, go to step 20 . If connection is okay, go to step 18 .
14. Check MAF sensor signal circuit for excessive resistance between PCM and MAF sensor connectors. Check for excessive resistance in sensor ground circuit. Check for MAF signal circuit shorted to sensor ground circuit. Check for poor connection at PCM. Repair as necessary. After repairs, go to step 20 . If circuits or connections are okay, go to step 19 .
15. Locate and repair open in MAF sensor ground circuit. After repairs, go to step 20 .
16. Locate and repair open or excessive resistance in MAF sensor ignition feed circuit. After repairs, go to step 20 .
17. Locate and repair short to voltage in MAF sensor signal circuit. After repairs, go to step 20 .
18. Replace MAF sensor. After replacing sensor, go to step 20 .
19. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
20. Using scan tool, review and record FAILURE RECORDS data. Clear DTCs. Start engine and operate vehicle as close to conditions recorded in FAILURE RECORDS as possible. Monitor SPECIFIC DTC info for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for sticking throttle plate. Check for carbon build-up on throttle plate and throttle bore. Check TP sensor. See ENGINE SENSORS & SWITCHES in appropriate SYSTEM & COMPONENT TESTING article. Check for poor connection at PCM. Check for misrouted or damaged MAF sensor wiring harness. Ensure harness is not close to high-voltage components.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start engine and allow it to idle. Using scan tool, observe MAF FREQUENCY. If MAF frequency is less than 1200 Hz, go to step 4 . If MAF frequency is not less than 1200 Hz, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Select SPECIFIC DTC function, and then enter this DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S30123785512000101600000) .
4. Check for blockage at MAF sensor inlet screen. Check for vacuum leaks around throttle body spacer, intake manifold, PCV system, EGR system, oil dipstick tube and oil filler cap. Check operation of PCV system. Repair as necessary. After repairs, go to step 14 . If no problems are found, go to next step.
5. Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on, with engine off. Using DVOM, check voltage between battery ground and signal circuit terminal at MAF sensor harness connector. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 9 .
6. Connect a test light between ignition feed circuit and ground circuit terminals at MAF sensor harness connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
7. Connect a test light between ground and ignition feed circuit terminal at MAF sensor harness connector. If test light illuminates, go to step 10 . If test light does not illuminate, go to step 11 .
8. Check for poor connection at MAF sensor connector. Repair as necessary. After repairs, go to step 15 . If connection is okay, go to step 12 .
9. Check MAF sensor signal circuit for open for short to ground, or short to voltage. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 14 .
10. Repair open in MAF sensor ground circuit. After repairs, go to step 15 .
11. Repair open in MAF sensor ignition feed circuit. After repairs, go to step 15 .
12. Replace MAF sensor. After replacing sensor, go to step 15 .
13. Repair poor connections at PCM. After repairs, go to next step.
14. Replace PCM. Perform PCM reprogramming procedures. After repairs, go to next step.
15. Using scan tool, clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P0102. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for poor connection at PCM. Check for misrouted MAF sensor wiring harness. Ensure harness is not close to high voltage components. Check for damaged wiring harness. Check for plugged intake air duct or filter element.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start engine and allow it to idle. Using scan tool, monitor MAF frequency. If MAF frequency is less than 11,500 Hz, go to step 4 . If MAF frequency is not less than 11,500 Hz, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S38356424082000101600000) .
4. Turn ignition off. Disconnect MAF sensor harness connector. Start engine. Using scan tool, monitor MAF frequency. If MAF frequency is zero Hz, go to next step. If MAF frequency is not zero Hz, go to step 7 .
5. Check for poor connection at MAF sensor connector. Repair as necessary. After repairs, go to step 10 . If connector is okay, go to next step.
6. Replace MAF sensor. After replacing sensor, go to step 10 .
7. Check for incorrect routing of MAF sensor wiring harness. Ensure harness is not near ignition coils or other high-voltage components. Reroute wiring harness as necessary. After repairs, go to step 10 . If wiring harness is routed correctly, go to next step.
8. Check MAF signal circuit terminal connections at PCM. Repair as necessary. After repairs, go to step 10 . If terminal connections are okay, go to next step.
9. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
10. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, read MAP sensor voltage. If voltage reading is less than 0.1 volt, go to step 4 . If voltage reading is not less than 0.1 volt, go to next step.
3. With ignition on, engine off, use scan tool to read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S19026575152000101600000) .
4. Disconnect MAP sensor harness connector. Connect a fused jumper wire between MAP sensor harness connector 5-volt reference circuit and signal circuit. If scan tool MAP voltage is about 4.95 volts, go to step 11 . If voltage is not about 4.95 volts, go to next step.
5. Turn ignition off. Remove jumper wire. Connect a test light between MAP sensor harness connector signal circuit and battery voltage. Turn ignition on. If voltage is about 4.95 volts, go to next step. If voltage is not 4.95 volts, go to step 8 .
6. Turn ignition off. Disconnect PCM connectors. Check PCM harness connector 5-volt reference circuit for an open or short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to next step.
7. Check for faulty connection of 5-volt reference circuit at PCM. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to step 12 .
8. Turn ignition off. Disconnect PCM connectors. Check PCM harness connector MAP signal circuit for an open, short to ground or short to sensor ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to next step.
9. Check for faulty connection of MAP signal circuit at PCM. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to step 12 .
10. Check MAP sensor signal circuit and 5-volt reference circuit for poor connection at PCM. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
11. Replace MAP sensor. After replacing sensor, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe MAP display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Correct any engine idle or vacuum problems before proceeding. Start engine and allow it to idle. Using scan tool, observe MAP sensor voltage. If voltage reading is greater than 4.2 volts, go to step 4 . If voltage reading is not greater than 4.2 volts, go to next step.
3. With ignition on, engine off, use scan tool to read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S25837832052000101600000) .
4. Turn ignition off. Disconnect MAP sensor harness connector. Turn ignition on, with engine off. Observe MAP sensor voltage parameter on scan tool. If voltage reading is zero volts, go to next step. If voltage reading is not zero volts, go to step 7 .
5. Check for plugged or leaking vacuum supply to MAP sensor. Repair as necessary. After repairs, go to step 12 . If no problems were found, go to next step.
6. Check MAP sensor ground circuit for continuity. Repair as necessary. After repairs, go to step 12 . If ground circuit is okay, go to step 8.
7. Check MAP sensor signal circuit for short to voltage. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 11 .
8. Check MAP sensor ground circuit for faulty connection at PCM harness connector. Repair as necessary. After repairs, go to step 12 . If connection is okay, go to next step.
9. Check MAP sensor ground circuit at MAP sensor for poor connections at harness connector. Repair as necessary. After repairs, go to step 12 . If connections are okay, go to next step.
10. Replace MAP sensor. After replacing sensor, go to step 12 .
11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
12. Turn ignition on, with engine off. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe MAP display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, observe IAT parameter. If IAT parameter is greater than 275°F (135°C), go to step 4 . If IAT parameter is not greater than 275°F (135°C), go to next step.
3. Turn ignition on, with engine off. Using scan tool, read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S13557477532000101600000) .
4. Turn ignition off. Disconnect IAT sensor harness connector. Turn ignition on, with engine off. Using scan tool, observe IAT parameter. If IAT parameter is less than -35°F (-37°C), go to step 6 . If IAT parameter is not less than -35°F (-37°C), go to next step.
5. Turn ignition off. Check IAT sensor signal circuit for short to ground. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to step 7 .
6. Replace IAT sensor. After replacing sensor, go to step 8 .
7. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
8. Turn ignition on, with engine off. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe IAT display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed IAT sensor. See appropriate SENSOR OPERATING RANGE CHARTS article.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Using scan tool, observe IAT parameter. If IAT parameter is less than -35°F (-37°C), go to step 4 . If IAT parameter is not less than -35°F (-37°C), go to next step.
3. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S21405782122000101600000) .
4. Turn ignition off. Disconnect IAT sensor harness connector. Connect a fused jumper wire between signal and ground circuits at IAT sensor harness connector. Using scan tool, observe IAT parameter. If IAT parameter is greater than 282°F (139°C), go to step 6 . If IAT parameter is not greater than 282°F (139°C), go to next step.
5. Connect jumper wire between chassis ground and IAT sensor harness connector signal circuit. Using scan tool, observe IAT parameter. If IAT parameter is greater than 282°F (139°C), go to step 7 . If IAT parameter is not greater than 282°F (139°C), go to step 8 .
6. Check IAT sensor signal circuit for short to voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 11 .
7. Check IAT sensor ground circuit for high resistance or open circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check IAT sensor signal circuit for open circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to next step.
9. Check for faulty IAT signal or ground circuit connection at PCM. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Check for faulty connections at IAT sensor. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to next step.
11. Replace IAT sensor. After replacing sensor, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe IAT display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location. Check for skewed IAT sensor. See appropriate SENSOR OPERATING RANGE CHARTS article.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, observe ECT parameter. If ECT parameter is greater than 282°F (139°C), go to step 4 . If ECT temperature is not greater than 282°F (139°C), go to next step.
3. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S03164860352000101600000) .
4. Turn ignition off. Disconnect ECT sensor harness connector. Using scan tool, observe ECT parameter. If ECT parameter is less than -36°F (-38°C), go to step 6 . If ECT parameter is not less than -36°F (-38°C), go to next step.
5. Check ECT sensor signal circuit for short to ground or short to sensor ground circuit. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to step 7 .
6. Replace ECT sensor. After replacing sensor, go to step 8 .
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe ECT display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

If DTC P0117 cannot be duplicated, the information included in the FAILURE RECORDS data can be useful in determining vehicle mileage since the DTC was last set. If it is determined that the DTC occurs intermittently, performing DTC P1114 diagnosis may isolate cause of fault.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe ECT parameter. If ECT parameter is less than -37°F (-39°C), go to step 4. If ECT parameter is not less than -37°F (-39°C), go to next step.
3. Turn ignition on, with engine off. Using scan tool, read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S33848347282000101600000) .
4. Check ECT sensor signal circuit for short to voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to next step.
5. Turn ignition off. Connect a fused jumper wire between ECT sensor harness connector signal and ground circuits. Using scan tool, observe ECT parameter. If ECT parameter is greater than 282°F (139°C), go to step 7 . If ECT parameter is not greater than 282°F (139°C), go to next step.
6. Connect jumper wire between chassis ground and ECT sensor harness connector signal circuit. Observe ECT parameter on scan tool. If ECT parameter is 282°F (139°C), go to step 8 . If ECT parameter is not greater than 282°F (139°C), go to step 9 .
7. Check for faulty connection at ECT sensor. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to step 11 .
8. Check ECT sensor ground circuit for an open. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 10 .
9. Check ECT signal circuit for an open. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to next step.
10. Check for faulty ECT signal or ground circuit connection at PCM. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
11. Replace ECT sensor. After replacing sensor, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Turn ignition on, with engine off. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe ECT display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

If DTC P0118 cannot be duplicated, the information included in the FAILURE RECORDS data can be useful in determining vehicle mileage since the DTC was last set. If it is determined that the DTC occurs intermittently, performing DTC P1115 diagnosis may isolate cause of fault.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe TP angle reading while slowly opening throttle. TP angle should increase steadily and evenly from closed throttle value (zero percent) to wide open throttle value (100 percent). If TP angle reading is as specified, see «DIAGNOSTIC AIDS»(ref-9296-S34933436952000101600000) . If TP angle reading is not as specified, go to next step.
3. Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on, with engine off. Using scan tool, observe the TP voltage parameter. If TP voltage parameter is about zero volts, go to next step. If TP voltage parameter is not about zero volts, go to step 5 .
4. Turn ignition off. Connect a fused jumper wire between the TP sensor harness connector 5-volt reference circuit and signal circuit. Turn ignition on, with engine off. Using scan tool, observe TP sensor voltage parameter. If TP sensor voltage parameter is 5 volts, go to step 8 . If TP sensor voltage parameter is not 5 volts, go to step 6 .
5. Check TP sensor signal circuit for short to voltage. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 11 .
6. Check TP sensor 5-volt reference circuit for high resistance or a poor connection at PCM. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to next step.
7. Check TP sensor signal circuit for high resistance, or a poor connection at PCM. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 11 .
8. Check TP sensor ground circuit for high resistance or a poor connection at PCM. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to next step.
9. Check for poor connections at TP sensor harness connector. Repair as necessary. After repairs, go to step 12 . If connections are okay, go to next step.
10. Replace TP sensor. After replacing sensor, go to step 12 .
11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
12. Using scan tool, clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for damaged or sticking throttle plate or IAC valve. A throttle valve place or IAC valve that allows too much airflow while throttle should be closed may cause a high idle and DTC P0121 to set.

A skewed MAP signal or faulty MAP sensor or an incorrect MAP signal may cause PCM to incorrectly calculate the predicted TP sensor value during high engine load situations. Check for an unusually low MAP reading. This condition can cause DTC to set.

Check for poor connections at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.

If DTC cannot be duplicated, the information included in the FAILURE RECORDS data can be useful in determining vehicle mileage since DTC was last set. If it is determined that DTC is intermittent, performing DTC P1121 or P1122 diagnosis may isolate cause of fault.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe TP sensor voltage parameter with throttle closed. If voltage reading is less than 0.16 volt, go to step 4 . If voltage is not less than 0.16 volt, go to next step.
3. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S23460268032000101600000) .
4. Turn ignition off. Connect a fused jumper wire between TP sensor harness connector 5-volt reference and signal circuits. If voltage reading is 5 volts, go to step 9 . If voltage reading is not 5 volts, go to next step.
5. Disconnect jumper wire. Using a DVOM, check voltage between ground and TP sensor 5-volt reference circuit at harness connector. If voltage reading is 5 volts, go to step 7 . If voltage reading is not 5 volts, go to next step.
6. Check TP sensor 5-volt reference circuit for high resistance, open or short to ground. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 8 .
7. Check TP sensor signal circuit for short to ground, high resistance, or an open in circuit. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to next step.
8. Check for faulty connection of TP signal circuit at PCM. Repair as necessary. After repairs, go to step 12 . If connection is okay, go to step 10 .
9. Check for poor connections of TP sensor harness connector. Repair as necessary. After repairs, go to step 12 . If connections are okay, go to next step.
10. Replace TP sensor. After replacing sensor, go to step 12 .
11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
12. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0122. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe TP sensor display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

If DTC cannot be duplicated, the information included in the FAILURE RECORDS data can be useful in determining vehicle mileage since DTC was last set. If it is determined that DTC is intermittent, performing DTC P1122 diagnosis may isolate cause of fault.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Using scan tool, observe TP sensor voltage with throttle closed. If voltage reading is greater than 4.9 volts, go to step 4 . If voltage reading is not greater than 4.9 volts, go to next step.
3. Using scan tool, read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S16872455892000101600000) .
4. Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on, with engine off. Using scan tool, observe TP sensor voltage parameter. If voltage parameter is about zero volts, go to next step. If voltage is not as specified, go to step 7 .
5. Using a DVOM, check voltage between TP sensor 5-volt reference circuit and a known-good ground. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step 9 .
6. Connect a test light between TP sensor harness connector ground circuit and battery positive. If test light illuminates, go to step 10 . If test light does not illuminate, go to next step.
7. Turn ignition off. Disconnect PCM harness connectors. Check TP sensor harness connector ground circuit for high resistance or open circuit. Repair as necessary. After repairs, go to step 14 . If circuit is okay, go to step 11 .
8. Check TP sensor signal circuit for short to voltage. Repairs as necessary. After repairs, go to step 14 . If circuit is okay, go to step 13 .
9. Check each component (one at a time) that shares common 5-volt reference circuit for short to voltage. Repair as necessary. After repairs, go to step 14 . If components or circuits are okay, go to step 13 .
10. Check for poor connection at TP sensor harness connector. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to step 12 .
11. Check for poor connections at PCM harness connector. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to step 13 .
12. Replace TP sensor. After replacing sensor, go to step 14 .
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Turn ignition on, with engine off. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Ensure harness is not routed too close to high-voltage wires, such as spark plug cables. If connections and harness appear okay, observe TP sensor display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Turn ignition on, engine off. Using scan tool TP sensor display, slowly depress accelerator to wide open throttle. If voltage is greater than 4.71 volts at any time, replace TP sensor.

If DTC cannot be duplicated, the information included in the FAILURE RECORDS data can be useful in determining vehicle mileage since DTC was last set. If it is determined that DTC is intermittent, performing DTC P1121 diagnosis may isolate cause of fault.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Check if any ECT related DTCs are set. Diagnose affected DTC(s) before proceeding. If no ECT related DTCs are set, go to next step.
3. Turn ignition off. Disconnect ECT sensor harness connector. Using a fused jumper wire, jumper ECT sensor harness connector terminals. Turn ignition on, with engine off. Using scan tool, observe ECT parameter. If ECT parameter is about 284°F (140°C), go to step 6 . If ECT parameter is not about 284°F (140°C), go to next step.
4. Check ECT sensor circuit for high resistance, poor connections at ECT sensor and PCM connectors. Repair as necessary. After repairs, go to next step. If circuit or connections are okay, go to step 7 .
5. Replace faulty terminals or faulty wiring as necessary. After repairs, go to step 8 .
6. Replace ECT sensor. After replacing sensor, go to next step.
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Allow engine to cool down until ECT and IAT sensor parameters are within 5 degrees of each other. Using scan tool, clear DTCs. Start and operate engine at idle. Monitor ECT parameter. If ECT parameter increases to greater than 14°F (-10°C) within 9 minutes, system is okay. If ECT parameter does not increase to greater than 14°F (-10°C) within 9 minutes, go to step 2 .

Check coolant level. Ensure thermostat and cooling fans are operating properly. Check for high resistance in wiring related to ECT sensor. Check for skewed ECT sensor by comparing actual coolant temperature with scan tool display, and replace ECT sensor if temperatures are not close.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

If DTC cannot be duplicated, the information included in the FAILURE RECORDS data can be useful in determining vehicle mileage since DTC was last set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, observe HO2S 1 voltage. If voltage remains less than 400 mV, go to step 4 . If voltage does not remain less than 400 mV, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within the conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until DTC P0131 test runs. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S35362918652000101600000) .
4. Disconnect HO2S 1 connector. Turn ignition on, with engine off. Observe HO2S 1 voltage on scan tool. If voltage reading is less than 400 mV, go to next step. If voltage is not less than 400 mV, go to step 7 .
5. Check HO2S signal circuit for short to ground or short to sensor ground circuit. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to next step.
6. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 8 .
7. Replace HO2S 1. After replacing sensor, go to next step.
8. Using scan tool, clear DTCs. Start engine and operate vehicle within conditions required for setting this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check HO2S pigtail wire for breaks, contamination or grounding on exhaust manifold. Check for intermittent ground in signal wire between sensor connector and sensor. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor. Check for fuel contamination, improper fuel pressure or exhaust leak, especially near oxygen sensor. Check for vacuum or crankcase leak, causing a lean condition. Check MAF sensor.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start engine and operate vehicle within conditions required for setting this DTC. Using scan tool, observe HO2S 1 voltage parameter. If voltage reading remains greater than 600 mV, go to step 5 . If voltage reading does not remain greater than 600 mV, go to next step.
3. Operate vehicle in DECEL FUEL MODE (vehicle speed greater than 25 MPH, TP angle less than 3 percent) while monitoring HO2S 1 on scan tool. If voltage reading remains greater than 110 mV, go to step 5 . If voltage reading does not remain greater than 110 mV, go to next step.
4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until DTC test runs. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S21566022082000101600000) .
5. Disconnect HO2S 1 connector. Observe scan tool display. If voltage reading is greater than 500 mV, go to next step. If voltage reading is not about 500 mV, go to step 8 .
6. Check for short to voltage in HO2S 1 signal circuit. Repair as necessary. After repairs, go to step 9 . If circuit is okay, go to next step.
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 9 .
8. Replace HO2S 1. After replacing sensor, go to next step.
9. Using scan tool, clear DTCs. Operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until DTC test runs. Recheck DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Check fuel pressure. Perform injector balance test. See appropriate SYSTEM & COMPONENT TESTING article. Check for leaking fuel pressure regulator by removing vacuum hose and checking for fuel presence. If fuel is present, replace regulator. Check EVAP canister for fuel saturation. Check MAF sensor. See appropriate SYSTEM & COMPONENT TESTING article.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Warm engine to normal operating temperature. Operate engine greater than 1200 RPM for 2 minutes. Using scan tool, observe HO2S voltage parameter. If HO2S voltage is varying out of 400-500 mV range, go to next step. If HO2S voltage is not varying out of 400-500 mV range, go to step 4 .
3. Operate vehicle within FAILURE RECORDS conditions. Does scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S07907857062000101600000) .
4. Check for exhaust leak, improperly installed HO2S or for damaged wiring. Repair as necessary. After repairs, go to step 15 . If no problems were found, go to next step.
5. Turn ignition on. Disconnect HO2S harness connector. Using a jumper wire, jumper HO2S harness connector signal circuit to a known-good ground. Using scan tool, observe HO2S voltage parameter. If HO2S voltage reading is greater than 400 mV, go to next step. If HO2S voltage reading is not greater than 400 mV, go to step 10 .
6. Remove jumper wire. Using a DVOM, check voltage between ground and HO2S harness connector signal circuit. If voltage reading is about 4.5 volts, go to next step. If voltage reading is not about 4.5 volts, go to step 9 .
7. Check voltage between ground and HO2S harness connector low circuit. If voltage reading is 5 volts, go to step 11 . If voltage reading is not 5 volts, go to next step.
8. Check HO2S low circuit for open or high resistance. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
9. Check HO2S signal circuit for open or high resistance. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
10. Check HO2S low circuit for short to ground. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 14 .
11. Check for faulty connections at HO2S connector. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
12. Check for fuel contamination, engine oil or coolant consumption. Check for improper use of RTV sealant. O2S contamination can result from inappropriate RTV sealant use (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove and visually inspect O2S in order to check for contamination. Eliminate source of contamination before replacing sensor. After replacing sensor, go to step 15 .
13. Check for faulty connections at PCM. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
15. Using scan tool, clear DTCs. Operate vehicle within Fail Record conditions. Recheck for DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, go to next step.
16. Check for other DTCs present. Diagnose affected DTCs. If no other DTCs are set, system is okay.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe HO2S 1 display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Warm engine to normal operating temperature. Operate engine greater than 1200 RPM for 2 minutes. Using scan tool, observe HO2S voltage parameter. If HO2S voltage is varying out of 400-500 mV range, go to next step. If HO2S voltage is not varying out of 400-500 mV range, go to step 4 .
3. Operate vehicle within FAILURE RECORDS conditions. Does scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S14170829982000101800000) .
4. Check for exhaust leak, improperly installed HO2S or for damaged wiring. Repair as necessary. After repairs, go to step 15 . If no problems were found, go to next step.
5. Turn ignition on. Disconnect HO2S harness connector. Using a jumper wire, jumper HO2S harness connector signal circuit to a known-good ground. Using scan tool, observe HO2S voltage parameter. If HO2S voltage reading is greater than 400 mV, go to next step. If HO2S voltage reading is not greater than 400 mV, go to step 10 .
6. Remove jumper wire. Using a DVOM, check voltage between ground and HO2S harness connector signal circuit. If voltage reading is about 4.5 volts, go to next step. If voltage reading is not about 4.5 volts, go to step 9 .
7. Check voltage between ground and HO2S harness connector low circuit. If voltage reading is 5 volts, go to step 11 . If voltage reading is not 5 volts, go to next step.
8. Check HO2S low circuit for open or high resistance. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
9. Check HO2S signal circuit for open or high resistance. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
10. Check HO2S low circuit for short to ground. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 14 .
11. Check for faulty connections at HO2S connector. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
12. Check for fuel contamination, engine oil or coolant consumption. Check for improper use of RTV sealant. O2S contamination can result from inappropriate RTV sealant use (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove and visually inspect O2S in order to check for contamination. Eliminate source of contamination before replacing sensor. After replacing sensor, go to step 15 .
13. Check for faulty connections at PCM. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
15. Using scan tool, clear DTCs. Operate vehicle within Fail Record conditions. Recheck for DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, go to next step.
16. Check for other DTCs present. Diagnose affected DTCs. If no other DTCs are set, system is okay.

Check for poor connection at PCM. Check for damaged wiring harness. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation.

Turn ignition on, with engine off. Using scan tool, monitor HO2S 1 voltage. Voltage should gradually drop to less than 250 mV or rise to greater than 600 mV. If voltage is not as specified, disconnect HO2S 1 connector. Connector a test light between ignition feed circuit and heater ground circuit terminals at HO2S 1 harness connector. If test light does not illuminate, repair open ignition feed circuit. If test light illuminates, replace HO2S 1.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Allow engine to completely cool down before proceeding. Turn ignition on, with engine off. Using scan tool, monitor HO2S 1 voltage. If voltage changes from about 300 mV to greater than 600 mV or from about 600 mV to less than 300 mV, see «DIAGNOSTIC AIDS»(ref-9296-S12382647252000101600000) . If voltage does not change as indicated, go to next step.
3. Remove and inspect fuse for HO2S 1 ignition feed circuit. If fuse is blown, go to step 13 . If fuse is okay, go to next step.
4. Turn ignition off. Disconnect HO2S 1 connector. With test light connected to ground, probe ignition feed circuit terminal at HO2S 1 harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 7 .
5. Connect a test light between HO2S 1 heater ground circuit and ignition feed circuit terminals at HO2S 1 harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
6. Allow HO2S 1 to cool for a minimum of 10 minutes. Using DVOM, check resistance between ignition feed circuit and heater ground circuit terminals at HO2S 1 pigtail. If resistance is 5-10 ohms, go to step 9 . If resistance is not 5-10 ohms, go to step 12 .
7. Repair open in HO2S 1 ignition feed circuit. After repairs, go to step 14 .
8. Repair open in HO2S 1 ignition feed circuit. After repairs, go to step 14 .
9. Check for poor connection at HO2S 1 harness terminals. Repair as necessary. After repairs, go to step 14 . If terminals are okay, go to next step.
10. Check for open in HO2S 1 harness connector signal and low circuit. Repair as necessary. After repairs, go to step 14 . If circuits are okay, go to next step.
11. Check HO2S signal or low circuits for faulty connection at PCM and HO2S connector. Repair as necessary. After repairs, go to step 14 . If circuits are okay, go to next step.
12. Replace HO2S 1. After replacing sensor, go to step 14 .
13. Repair short to ground in HO2S 1 ignition feed circuit. Replace fuse. After repairs, go to next step.
14. Allow engine to completely cool down before proceeding. Using scan tool, clear DTCs. Turn ignition on, with engine off. Using scan tool, monitor HO2S 1 voltage for at least 2 minutes. If voltage changes from about 300 mV to greater than 600 mV or from about 600 mV to less than 300 mV, system is okay. If voltage does not change as indicated, go to step 2 .

Check for poor connection at PCM. Check for damaged wiring harness. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start engine and allow it to reach operating temperature. Operate vehicle under conditions required to set DTC. Using scan tool, read HO2S 2 voltage. If voltage remains less than 100 mV, go to step 4 . If voltage is not specified, go to next step.
3. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S05177400422000101600000) .
4. Disconnect HO2S 2 harness connector. Connect a jumper wire between HO2S 2 harness connector ground circuit and chassis ground. If voltage is about 450 mV, see «DIAGNOSTIC AIDS»(ref-9296-S05177400422000101600000) . If voltage is not as specified, go to next step.
5. Turn ignition off. Disconnect PCM harness connectors. Check HO2S 2 sensor harness connector signal circuit for short to ground or short to sensor ground. If short is found, go to next step. If circuit is okay, go to step 7 .
6. Repair HO2S 2 signal circuit. After repairs, go to step 8 .
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Turn ignition on, engine off. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Ensure HO2S 2 sensor harness is routed correctly and not contacting exhaust system. Check for faulty PCM grounds. Check fuel system. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article. Perform injector balance test. See appropriate SYSTEM & COMPONENT TESTING article.

Check for vacuum leaks at intake manifold, throttle body, EGR system and crankcase ventilation system. Check for exhaust leaks in front of HO2S 2. Disconnect MAF sensor connector and see if lean condition is corrected. If lean condition is corrected, replace MAF sensor. Check for fuel contamination.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start engine and allow it to reach normal operating temperature. Operate vehicle under conditions required to set DTC. Using scan tool, monitor HO2S 2 voltage. If voltage remains greater than 999 mV, go to step 4 . If voltage does not remain greater than 999 mV, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info this DTC until DTC test runs. If scan tool indicates test failed this ignition, go to next step. If scan tool does not indicated test failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S02526524772000101600000) .
4. Disconnect HO2S 2 harness connector. Connect a jumper wire between ground and sensor ground circuit terminal at HO2S 2 harness connector. If voltage is about 450 mV, see «DIAGNOSTIC AIDS»(ref-9296-S02526524772000101600000) . If voltage is not about 450 mV, go to next step.
5. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Measure voltage between ground and HO2S 2 signal circuit terminal at PCM harness connector. If voltage is greater than 999 mV, go to next step. If voltage is not greater than 999 mV, go to step 7 .
6. Repair short to voltage in HO2S 2 signal circuit. After repairs, go to step 8 .
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Using scan tool, clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until DTC test runs. If scan tool indicates test failed this ignition, go to step 2 . If scan tool does not indicate test failed this ignition, system is okay.

Check if fuel pressure is too high. PCM can compensate for some increase; however, if fuel pressure is too high, DTC will set. Check for leaking injector(s) or faulty fuel pressure regulator. See appropriate SYSTEM & COMPONENT TESTING article. Check EVAP system for fuel saturation. Check MAF sensor. Check oxygen sensor for silicone contamination. Check TP sensor. See appropriate SYSTEM & COMPONENT TESTING article.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start engine and allow it to reach operating temperature. Place gear selector in Park or Neutral, and apply parking brake. Increase engine speed to greater than 1200 RPM for 2 minutes. Using scan tool, read HO2S 2 voltage. If voltage is varying outside of 400-500 mV range, go to next step. If voltage is varying as specified, go to step 4 .
3. Turn engine off. Turn ignition on, with engine off. Using scan tool, read and record FAILURE RECORDS data. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S20503991602000101600000) .
4. Disconnect HO2S 2 harness connector. Connect a jumper wire between ground and HO2S 2 harness connector signal and low circuits. If voltage reading is less than 150 mV, go to step 8 . If voltage reading is not less than 150 mV, go to next step.
5. Remove jumper wire. Using DVOM, check voltage between HO2S 2 harness connector signal and heater ground circuits. If voltage reading is about 950 mV, go to next step. If voltage reading is not about 950 mV, go to step 7 .
6. Turn ignition off. Disconnect PCM harness connectors. Check resistance of HO2S 2 harness connector ground circuit. If resistance is greater than 5 ohms, repair open or faulty connection. After repairs, go to step 13 . If resistance is not greater than 5 ohms, go to step 9 .
7. Turn ignition off. Disconnect PCM harness connectors. Check resistance of HO2S 2 harness connector signal circuit. If resistance is greater than 5 ohms, repair open or faulty connection. After repairs, go to step 13 . If resistance is not greater than 5 ohms, go to step 10 .
8. Check for faulty connection at HO2S 2. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to step 11 .
9. Check HO2S 2 ground circuit for faulty connection at PCM. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to step 12 .
10. Check HO2S 2 signal circuit for faulty connection at PCM. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to step 12 .
11. Replace HO2S 2. After replacing sensor, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe HO2S 2 display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location. Check HO2S 2 heater operation.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Using scan tool, read HO2S 2 voltage. If voltage reading is greater than 600 mV or less than 300 mV, see «DIAGNOSTIC AIDS»(ref-9296-S04372208882000101600000) . If voltage reading is not is greater than 600 mV or less than 300 mV, go to next step.
3. Inspect HO2S 2 ignition feed fuse. If fuse is open, go to step 15 . If fuse is okay, go to next step.
4. Disconnect HO2S 2 harness connector. Connect a test light between chassis ground and HO2S 2 ignition feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 7 .
5. Connect test light between HO2S 2 harness connector ignition feed and heater ground circuits. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
6. Allow HO2S 2 to cool for at least 10 minutes. Using DVOM, check resistance between ignition feed and heater ground circuits at HO2S 2. If resistance is 5-6 ohms, go to step 9 . If resistance is not 5-6 ohms, go to step 14 .
7. Repair open HO2S 2 ignition feed circuit. After repairs, go to step 16 .
8. Repair open HO2S 2 heater ground circuit. After repairs, go to step 16 .
9. Check for faulty connection at HO2S 2. Repair as necessary. After repairs, go to step 16 . If connection is okay, go to next step.
10. Turn ignition off. Disconnect PCM harness connectors. Check resistance of HO2S 2 signal and ground circuits. If resistance on either circuit is greater than 5 ohms, repair open or faulty connection as necessary. After repairs, go to step 16 . If resistance is not greater than 5 ohms, go to next step.
11. Check for faulty connection at HO2S 2 harness connector. Repair as necessary. After repairs, go to step 16 . If connection is okay, go to next step.
12. Check for faulty HO2S 2 ground circuit connection at PCM. Repair as necessary. After repairs, go to step 16 . If connection is okay, go to next step.
13. Check for faulty HO2S 2 signal circuit connection at PCM. Repair as necessary. After repairs, go to step 16 . If connection is okay, go to next step.
14. Replace HO2S 2. After replacing sensor, go to step 16 .
15. Locate and repair short to ground in HO2S 2 ignition feed circuit and replace fuse. After repairs, go to next step.
16. Allow engine to cool completely. Using scan tool, clear DTCs. Turn ignition on, engine off. Read HO2S 2 voltage. If voltage reading is greater than 600 mV or less than 300 mV, system is okay. If voltage reading is not greater than 600 mV, go to step 2 .

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Operate vehicle in closed loop mode while using scan tool to read LT and ST FUEL TRIM values. If LT FUEL TRIM value is about +16 percent and ST FUEL TRIM value is about +20 percent, go to step 5 . If values are not as specified, go to next step.
4. Using scan tool, read and record FAILURE RECORDS data. Clear DTCs and operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC while operating vehicle. Continue operating vehicle until DTC P0171 test runs. If scan tool indicates that DTC P0171 failed this ignition, go to next step. If scan tool does not indicate that DTC P0171 failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S10316474292000101600000) .
5. Check vacuum hoses for splits, kinks and proper routing. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
6. Check PCV valve for proper installation. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
7. Check throttle body inlet screen for blockage or foreign objects which may partially block airflow sample through MAF sensor. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
8. Start engine. If high or unsteady idle condition exists, go to next step. If Idle is okay, go to step 11 .
9. Using scan tool, read IDLE AIR CONTROL (IAC) value. If value is greater than 5 counts, go to step 11 . If value is not greater than 5 counts, go to next step.
10. Check throttle body, intake manifold, and EGR valve for vacuum leaks. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
11. Check IAC valve for proper operation. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
12. Check for fuel contamination. If fuel is contaminated, repair condition causing contamination. After repairs, go to step 22 . If fuel is okay, go to next step.
13. Check PCM injector, power and sensor grounds for clean and tight connection, and for proper location. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
14. Disconnect MAF sensor harness connector. Operate vehicle in closed loop mode while monitoring scan tool ST FUEL TRIM. If ST FUEL TRIM decreases to about zero percent, go to step 21 . If ST FUEL TRIM does not decrease to about zero percent, go to next step.
15. Check fuel pressure. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
16. Perform EVAP system check. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
17. Check intake manifold, injector "O" rings, EGR adapter, EGR valve, and EGR feed pipes for vacuum leaks. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
18. Check exhaust system for corrosion, loose or missing hardware. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
19. Perform INJECTOR BALANCE TEST. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, go to next step.
20. Ensure HO2S is installed securely, and connector and harness are not contacting exhaust manifold or ignition wires. If a problem is found, repair as necessary. After repairs, go to step 22 . If no problem is found, see «DIAGNOSTIC AIDS»(ref-9296-S10316474292000101600000) .
21. Replace MAF sensor. After replacing sensor, go to next step.
22. Using scan tool, read and record FAILURE RECORDS data, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Ensure HO2S wiring is routed correctly and not contacting exhaust system. Check for faulty PCM-to-engine ground connections. Check fuel pressure. Check fuel injector operation. Check for vacuum and exhaust leaks. Disconnect MAF sensor connector and see if lean condition is corrected. If lean condition is corrected, replace MAF sensor.

Check for fuel contamination. Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool HO2S 1 display while moving all related harness and connectors. A change in scan tool display indicates fault location.

Circuit Description

PCM monitors oxygen sensor signal voltage and adjusts fuel delivery based on signal voltage. A change made to fuel delivery is indicated by the long and short term fuel trim values. Ideal fuel trim value is about 128 (zero percent).

If HO2S signals are indicating a lean condition, the PCM will add fuel, resulting in fuel trim values greater than zero percent. If a rich condition is detected, fuel trim values will be less than zero percent, indicating that PCM is reducing amount of fuel delivered.

For duplication of DTC, ensure

1. No active misfire, fuel injector circuit, EVAP system, fuel trim, TP, IAT, MAP, EGR, ECT, MAF or CKP sensor DTCs are set.
2. ECT is 68-230°F (20-110°C).
3. IAT is 0-149°F (-18 to 65°C).
4. TP sensor angle is less than 90 percent.
5. Vehicle speed is less than 75 MPH.
6. Engine speed is 600-4000 RPM.
7. Air flow between 3-150 grams per second.
8. BARO is greater than 70 kPa.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. If any other DTCs are set, diagnose DTCs as necessary before proceeding. If no other DTCs are set, go to next step.
3. Start and warm engine to normal operating temperature. Ensure system is in closed loop. Using scan tool, select ENG 1 data list. Observe L.T. FUEL TRIM and S.T. FUEL TRIM. If L.T. FUEL TRIM is about -16 percent and S.T. FUEL TRIM is about -11 percent, go to step 5 . If fuel trim is not as specified, go to next step.
4. Using scan tool, clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until DTC test runs. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S21753853392000101600000) .
5. Inspect air filter element. Replace as necessary. After repairs, go to step 21 . If air filter element is okay, go to next step.
6. Check for collapsed or restricted air intake duct. Repair as necessary. After repairs, go to step 21 . If air duct is okay, go to next step.
7. Inspect throttle body inlet screen for damage or blockage. Repair as necessary. After repairs, go to step 21 . If inlet screen is okay, go to next step.
8. Start engine and check idle quality. If idle is high or rough, go to next step. If idle is okay, go to step 11 .
9. Allow engine to idle. Using scan tool, observe IDLE AIR CONTROL display. If counts are greater than 100, go to step 11 . If counts are not greater than 100, go to next step.
10. Turn ignition off. Inspect throttle body bore, throttle plate and IAC passages for coking and foreign objects. Repair as necessary. After repairs, go to step 21 . If no problem is found, go to next step.
11. Check Idle Air Control (IAC) valve operation. See appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. After repairs, go to step 21 . If IAC valve is functioning properly, go to step 13 .
12. Disconnect vacuum hose from fuel pressure regulator and check hose for presence of fuel. If fuel is present, replace fuel pressure regulator. After repairs, go to step 21 . If fuel pressure regulator is okay, go to next step.
13. Turn ignition on. Monitor TP angle display on scan tool while slowly depressing accelerator pedal. If TP angle display increase steadily from 0-100 percent (wide-open throttle), go to next step. If TP angle display does not increase as specified, go to step 19 .
14. Disconnect MAF sensor harness connector. Start engine and allow it to idle. Ensure system is in closed loop. Using scan tool, observe ST FUEL TRIM and LT FUEL TRIM display. If both values change to about zero percent, go to step 21 . If one or both values do not change to about zero percent, go to next step.
15. Diagnose fuel system. See appropriate BASIC DIAGNOSTIC PROCEDURES article. Repair fuel system as necessary. After repairs, go to step 21 . If fuel system is okay, go to next step.
16. Check fuel evaporation system for proper operation. Ensure canister purge solenoid is functioning properly. See appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. After repairs, go to step 21 . If fuel evaporation system is functioning properly, go to next step.
17. Perform injector balance test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. After repairs, go to step 21 . If no problems were found, go to next step.
18. Visually and physically inspect HO2S 1 for silicon contamination (White powdery deposits). If contamination is evident, replace sensor. After repairs, go to step 21 . If sensor is okay, see «DIAGNOSTIC AIDS»(ref-9296-S21753853392000101600000) .
19. Check TP sensor mounting screws. Tighten or replace mounting screws as necessary. If mounting screws are okay, replace TP sensor. After repairs, go to step 21 .
20. Replace MAF sensor. After replacing sensor, go to next step.
21. Using scan tool, clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info until this DTC test runs. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for poor connection at PCM. Check for damaged wiring harness. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition cycle, go to step 4 . If scan does not indicate that this DTC failed this ignition cycle, go to next step.
3. Turn ignition on, engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle in failure conditions parameter. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S27189426132000101600000) .
4. Using scan tool, enter OUTPUT DRIVER DATA menu. If scan tool indicates that cylinder No. 1 injector circuit is STUCK HIGH, go to step 6 . If scan tool does not indicate that cylinder No. 1 injector circuit is STUCK HIGH, go to next step.
5. If scan tool indicates that cylinder No. 1 injector circuit is STUCK LOW, go to step 10 . If scan tool does not indicate that cylinder No. 1 injector circuit is STUCK LOW, see «DIAGNOSTIC AIDS»(ref-9296-S27189426132000101600000) .
6. Turn ignition off. Disconnect 10-pin fuel injector harness connector. Crank engine. While cranking engine, if scan tool indicates that cylinder No. 1 injector circuit is STUCK LOW, go to next step. If scan tool does not indicate that cylinder No. 1 injector circuit is STUCK LOW, go to step 9 .
7. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Check voltage between cylinder No. 1 fuel injector control circuit and ground. If voltage reading is about battery voltage, go to next step. If voltage reading is not about battery voltage, go to step 15 .
8. Locate and repair short to voltage in cylinder No. 1 fuel injector control circuit. After repairs, go to step 16 .
9. If scan tool indicates that No. 1 injector control circuit is STUCK LOW, check affected fuel injector. Perform fuel injector coil test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.
10. Disconnect 10-pin fuel injector harness connector. Using a test light connected to battery positive, probe injector No. 1 control circuit at PCM side of 10-pin connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
11. Disconnect PCM harness connector. Using a test light connected to battery positive, probe injector No. 1 control circuit at PCM connector. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
12. With test light still connected, crank engine. If test light flashes, check affected fuel injector. Perform fuel injector coil test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If test light does not flash, go to next step.
13. Check cylinder No. 1 injector driver circuit between 10-pin injector connector and PCM for an open circuit. Repair as necessary. After repairs, go to step 16 .
14. Locate and repair short to ground in fuel injector driver circuit between PCM and 10-pin injector connector. After repairs, go to step 16 .
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle within FAILURE RECORDS conditions. Check for DTCs. If this DTC is set, go to step 2 . If this DTC is not set, system is okay.

Monitor injector fault parameter on scan tool. Wiggle electrical harnesses for affected electrical circuit. If status changes on tool, an intermittent problem is present. Check for poor connections at PCM. Check for damaged harness.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition cycle, go to step 4 . If scan does not indicate that this DTC failed this ignition cycle, go to next step.
3. Turn ignition on, engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle in failure conditions parameter. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S06404403842000101600000) .
4. Using scan tool, enter OUTPUT DRIVER DATA menu. If scan tool indicates that cylinder No. 2 injector circuit is STUCK HIGH, go to step 6 . If scan tool does not indicate that cylinder No. 2 injector circuit is STUCK HIGH, go to next step.
5. If scan tool indicates that cylinder No. 2 injector circuit is STUCK LOW, go to step 10 . If scan tool does not indicate that cylinder No. 2 injector circuit is STUCK LOW, see «DIAGNOSTIC AIDS»(ref-9296-S06404403842000101600000) .
6. Turn ignition off. Disconnect 10-pin fuel injector harness connector. Crank engine. While cranking engine, if scan tool indicates that cylinder No. 2 injector circuit is STUCK LOW, go to next step. If scan tool does not indicate that cylinder No. 2 injector circuit is STUCK LOW, go to step 9 .
7. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, with engine off. Check voltage between cylinder No. 2 fuel injector control circuit and ground. If voltage reading is about battery voltage, go to next step. If voltage reading is not about battery voltage, go to step 15 .
8. Locate and repair short to voltage in cylinder No. 2 fuel injector control circuit. After repairs, go to step 16 .
9. If scan tool indicates that No. 2 injector control circuit is STUCK LOW, check affected fuel injector. Perform fuel injector coil test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.
10. Disconnect 10-pin fuel injector harness connector. Using a test light connected to battery positive, probe injector No. 2 control circuit at PCM side of 10-pin connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
11. Disconnect PCM harness connector. Using a test light connected to battery positive, probe injector No. 2 control circuit at PCM connector. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
12. With test light still connected, crank engine. If test light flashes, check affected fuel injector. Perform fuel injector coil test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If test light does not flash, go to next step.
13. Check cylinder No. 2 injector driver circuit between 10-pin injector connector and PCM for an open circuit. Repair as necessary. After repairs, go to step 16 .
14. Locate and repair short to ground in fuel injector driver circuit between PCM and 10-pin injector connector. After repairs, go to step 16 .
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle with the FAILURE RECORDS conditions. Check for DTCs. If this DTC is set, go to step 2 . If this DTC is not set, system is okay.

Monitor injector fault parameter on scan tool. Wiggle electrical harnesses for affected electrical circuit. If status changes on tool, an intermittent problem is present. Check for poor connections at PCM. Check for damaged harness.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition cycle, go to step 4 . If scan does not indicate that this DTC failed this ignition cycle, go to next step.
3. Turn ignition on, engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle in failure conditions parameter. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S39742460922000101600000) .
4. Using scan tool, enter OUTPUT DRIVER DATA menu. If scan tool indicates that cylinder No. 3 injector circuit is STUCK HIGH, go to step 6 . If scan tool does not indicate that cylinder No. 3 injector circuit is STUCK HIGH, go to next step.
5. If scan tool indicates that cylinder No. 3 injector circuit is STUCK LOW, go to step 10 . If scan tool does not indicate that cylinder No. 3 injector circuit is STUCK LOW, see «DIAGNOSTIC AIDS»(ref-9296-S39742460922000101600000) .
6. Turn ignition off. Disconnect 10-pin fuel injector harness connector. Crank engine. While cranking engine, if scan tool indicates that cylinder No. 3 injector circuit is STUCK HIGH, go to next step. If scan tool does not indicate that cylinder No. 3 injector circuit is STUCK HIGH, go to step 9 .
7. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, with engine off. Measure voltage between cylinder No. 3 fuel injector control circuit and ground. If voltage reading is about battery voltage, go to next step. If battery voltage is not about battery voltage, go to step 15 .
8. Locate and repair short to voltage in cylinder No. 3 fuel injector control circuit. After repairs, go to step 16 .
9. If scan tool indicates that No. 3 injector control circuit is STUCK LOW, check affected fuel injector. Perform fuel injector coil test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.
10. Disconnect 10-pin fuel injector harness connector. Using a test light connected to battery positive, probe injector No. 3 control circuit at PCM side of 10-pin connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
11. Disconnect PCM harness connector. Using a test light connected to battery positive, probe injector No. 3 control circuit at PCM harness connector. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
12. With test light still connected, crank engine. If test light flashes, check affected fuel injector. Perform fuel injector coil test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If test light does not flash, go to next step.
13. Check cylinder No. 3 injector driver circuit between 10-pin injector harness connector and PCM for an open circuit. Repair as necessary. After repairs, go to step 16 .
14. Locate and repair short to ground in fuel injector driver circuit between PCM and 10-pin injector harness connector. After repairs, go to step 16 .
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle with the FAILURE RECORDS conditions. Check for DTCs. If this DTC is set, go to step 2 . If this DTC is not set, system is okay.

Monitor injector fault parameter on scan tool. Wiggle electrical harnesses for affected electrical circuit. If status changes on tool, an intermittent problem is present. Check for poor connections at PCM. Check for damaged harness.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition cycle, go to step 4 . If scan does not indicate that this DTC failed this ignition cycle, go to next step.
3. Turn ignition on, engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle in failure conditions parameter. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S41121478832000101600000) .
4. Using scan tool, enter OUTPUT DRIVER DATA menu. If scan tool indicates that cylinder No. 4 injector circuit is STUCK HIGH, go to step 6 . If scan tool does not indicate that cylinder No. 4 injector circuit is STUCK HIGH, go to next step.
5. If scan tool indicates that cylinder No. 4 injector circuit is STUCK LOW, go to step 10 . If scan tool does not indicate that cylinder No. 4 injector circuit is STUCK LOW, see «DIAGNOSTIC AIDS»(ref-9296-S41121478832000101600000) .
6. Turn ignition off. Disconnect 10-pin fuel injector harness connector. Crank engine. While cranking engine, if scan tool indicates that cylinder No. 4 injector circuit is STUCK HIGH, go to next step. If scan tool does not indicate that cylinder No. 4 injector circuit is STUCK HIGH, go to step 9 .
7. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Check voltage between cylinder No. 4 fuel injector control circuit and ground. If voltage reading is about battery voltage, go to next step. If voltage is not about battery voltage, go to step 15 .
8. Locate and repair short to voltage in cylinder No. 4 fuel injector control circuit. After repairs, go to step 16 .
9. If scan tool indicates that No. 4 injector control circuit is STUCK LOW, check affected fuel injector. Perform fuel injector coil test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.
10. Disconnect 10-pin fuel injector harness connector. Using a test light connected to battery positive, probe injector No. 4 control circuit at PCM side of 10-pin connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
11. Disconnect PCM harness connector. Using a test light connected to battery positive, probe injector No. 4 control circuit at PCM harness connector. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
12. With test light still connected, crank engine. If test light flashes, check affected fuel injector. Perform fuel injector coil test. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If test light does not flash, go to next step.
13. Check cylinder No. 4 injector driver circuit between 10-pin injector connector and PCM for an open circuit. Repair as necessary. After repairs, go to step 16 .
14. Locate and repair short to ground in fuel injector driver circuit between PCM and 10-pin injector connector. After repairs, go to step 16 .
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle with the FAILURE RECORDS conditions. Check for DTCs. If this DTC is set, go to step 2 . If this DTC is not set, system is okay.

Monitor injector fault parameter on scan tool. Wiggle electrical harnesses for affected electrical circuit. If status changes on tool, an intermittent problem is present. Check for poor connections at PCM. Check for damaged harness.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition cycle, go to step 4 . If scan does not indicate that this DTC failed this ignition cycle, go to next step.
3. Turn ignition on, engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle in fail conditions parameter. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S41457542472000101600000) .
4. Using scan tool, enter OUTPUT DRIVER DATA menu. If scan tool indicates that cylinder No. 5 injector circuit is STUCK HIGH, go to step 6 . If scan tool does not indicate that cylinder No. 5 injector circuit is STUCK HIGH, go to next step.
5. If scan tool indicates that cylinder No. 5 injector circuit is STUCK LOW, go to step 10 . If scan tool does not indicate that cylinder No. 5 injector circuit is STUCK LOW, see «DIAGNOSTIC AIDS»(ref-9296-S41457542472000101600000) .
6. Turn ignition off. Disconnect 10-pin fuel injector connector. Crank engine. While cranking engine, if scan tool indicates that cylinder No. 5 injector circuit is STUCK LOW, go to next step. If scan tool does not indicate that cylinder No. 5 injector circuit is STUCK LOW, go to step 9 .
7. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Check voltage between cylinder No. 5 fuel injector control circuit and ground. If voltage reading is battery voltage, go to next step. If voltage reading is not battery voltage, go to step 15 .
8. Locate and repair short to voltage in cylinder No. 5 fuel injector control circuit. After repairs, go to step 16 .
9. If scan tool indicates that No. 5 injector control circuit is STUCK LOW, check affected fuel injector. See appropriate SYSTEM & COMPONENT TESTING article.
10. Disconnect 10-pin fuel injector harness connector. Using a test light connected to battery voltage, probe injector No. 5 control circuit at PCM side of 10-pin connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
11. Disconnect PCM harness connector. Using a test light connected to battery voltage, probe injector No. 5 control circuit at PCM connector. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
12. With test light still connected, crank engine. If test light flashes, check affected fuel injector. See appropriate SYSTEM & COMPONENT TESTING article. If test light does not flash, go to next step.
13. Check cylinder No. 5 injector driver circuit between 10-pin injector connector and PCM for an open circuit. Repair as necessary. After repairs, go to step 16 .
14. Locate and repair short to ground in fuel injector driver circuit between PCM and 10-pin injector connector. After repairs, go to next step.
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle with the FAILURE RECORDS conditions. Check for DTCs. If this DTC is set, go to step 2 . If this DTC is not set, system is okay.

Monitor injector fault parameter on scan tool. Wiggle electrical harnesses for affected electrical circuit. If status changes on tool, an intermittent problem is present. Check for poor connections at PCM. Check for damaged harness.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition cycle, go to step 4 . If scan tool does not indicate that this DTC failed this ignition cycle, go to next step.
3. Turn ignition on, engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle in fail conditions parameter. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S10373872752000101600000) .
4. Using scan tool, enter OUTPUT DRIVER DATA menu. If scan tool indicates that cylinder No. 6 injector circuit is STUCK HIGH, go to step 6 . If scan tool does not indicate that cylinder No. 6 injector circuit is STUCK HIGH, go to next step.
5. If scan tool indicates that cylinder No. 6 injector circuit is STUCK LOW, go to step 10 . If scan tool does not indicate that cylinder No. 6 injector circuit is STUCK LOW, see «DIAGNOSTIC AIDS»(ref-9296-S10373872752000101600000) .
6. Turn ignition off. Disconnect 10-pin fuel injector connector. Crank engine. While cranking engine, if scan tool indicates that cylinder No. 6 injector circuit is STUCK LOW, go to next step. If scan tool does not indicate that cylinder No. 6 injector circuit is STUCK LOW, go to step 9 .
7. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Check voltage between cylinder No. 6 fuel injector control circuit and ground. If voltage reading is about battery voltage, go to next step. If voltage reading is not about battery voltage, go to step 15 .
8. Locate and repair short to voltage in cylinder No. 6 fuel injector control circuit. After repairs, go to step 16 .
9. If scan tool indicates that No. 6 injector control circuit is STUCK LOW, check affected fuel injector. See appropriate SYSTEM & COMPONENT TESTING article.
10. Disconnect 10-pin fuel injector harness connector. Using a test light connected to battery voltage, probe injector No. 6 control circuit at PCM side of 10-pin connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
11. Disconnect PCM harness connector. Using a test light connected to battery voltage, probe injector No. 6 control circuit at PCM connector. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
12. With test light still connected, crank engine. If test light flashes, check affected fuel injector. See appropriate SYSTEM & COMPONENT TESTING article. If test light does not flash, go to next step.
13. Check cylinder No. 6 injector driver circuit between 10-pin injector connector and PCM for an open circuit. Repair as necessary. After repairs, go to step 16 .
14. Locate and repair short to ground in fuel injector driver circuit between PCM and 10-pin injector connector. After repairs, go to next step.
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle with the FAILURE RECORDS conditions. Check for DTCs. If this DTC is set, go to step 2 . If this DTC is not set, system is okay.

Monitor injector fault parameter on scan tool. Wiggle electrical harnesses for affected electrical circuit. If status changes on tool, an intermittent problem is present. Check for poor connections at PCM. Check for damaged harness.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using a scan tool, command fuel pump relay on and off. If relay turns on and off with each command, see «DIAGNOSTIC AIDS»(ref-9296-S03753630922000101600000) . If relay does not turn on and off with each command, go to next step.
3. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Using a test light connected to ground, probe relay control circuit. Using scan tool, command relay on and off. If test light turns on and off with each command, go to next step. If test light does not turn on and off with each command, go to step 5 .
4. Connect test light between relay control and ground circuits. Using scan tool, command relay on and off. If test light turn on and off with each command, go to step 8 . If test light does not turn on and off with each command, go to step 10 .
5. If test light remains illuminated with each command, go to step 7 . If test light does not remain illuminated with each command, go to next step.
6. Check relay control circuit for short to ground or an open circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check relay control circuit for short to voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for poor connections at relay. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair relay ground circuit. After repairs, go to step 13 .
11. Replace relay. After replacing relay, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .

Scan tool will appear not to run if diagnostic passes. Using FREEZE FRAME and/or FAILURE RECORDS may aid in locating an intermittent condition. An intermittent may be caused by a poor connection, rubbed-through wire insulation or a wire broken inside of insulation. Check for poor connections at PCM or fuel pump relay.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Check for any other DTCs that are set. Diagnose affected DTC(s). If no other DTCs are set, go to next step.
3. Start and operate engine at idle. Using scan tool, review and record FREEZE FRAME data. Operate vehicle within conditions for setting this DTC. Monitor Misfire Current Cyl # display for each cylinder. If Misfire Current # display is incrementing for any cylinder (indicating a misfire currently occurring), go to step 5 . If Misfire Current # display is not incrementing for any cylinder, go to next step.
4. View Misfire History Cyl # display on scan tool. If Misfire History Cyl # display a very large value for more than one cylinder, go to next step. If Misfire History Cyl # does not display a very large value for more than one cylinder, go to step 8 .
5. If misfire values displayed on Misfire History Cyl # related to companion cylinders, go to step 9 . If misfire values displayed on Misfire History Cyl # is not related to companion cylinders, go to next step.
6. Check vacuum hoses for improper connections and damage. Check spark plug wire connections at coils and spark plugs. Check engine and PCM grounds. Ensure that connections are clean, tight and in their proper locations. Check EGR to intake manifold piping for proper connections and signs of damage. Repair as necessary. After repairs, go to step 22 . If no problems were found, go to next step.
7. Check fuel pressure. If fuel pressure 52-59 psi (3.6-4.2 kg/cm 2 ), go to next step. If fuel pressure is not 52-59 psi (3.6-4.2 kg/cm 2 ), diagnose fuel system. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
8. Check for proper fuel injector operation. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary. After repairs, go to step 22 . If no problems were found, go to next step.
9. Visually inspect ignition wires and coils associated with misfiring cylinders for carbon tracking/arching and damage, connected to incorrect cylinders at coil and spark plug, poor terminal connections at coil and spark plug. Replace affected ignition wire and associated ignition coil. After repairs, go to step 22 . If no problems were found, go to next step.
10. Using a spark tester (J 26792) at spark plug end of ignition wire associated with misfiring cylinders, jumper spark plug end of companion cylinder ignition wire to engine ground. Crank engine while observing spark tester. If spark is present, go to step 15 . If spark is not present, go to next step.
11. Check resistance of ignition wires associated with cylinders that were indicated as misfiring. Resistance should be 600 ohms per foot. Replace ignition wires as necessary. After repairs, go to step 22 . If ignition wire are okay, go to next step.
12. Check resistance of secondary ignition coils associated with misfiring cylinders. Resistance should be 5000-8000 ohms. Replace secondary ignition coil as necessary. After replacing coils, go to step 22 . If resistance is as specified, go to next step.
13. Remove ignition coils associated with misfiring cylinders. Check coils for signs of carbon tracking, cracks, or other damage. Replace affected coils as necessary. After replacing coils, go to step 22 . If coils are okay, go to next step.
14. Leave ignition coils disconnected. Connect a test light across ignition module primary circuit terminals. Remove fuel injector fuse. Observe test light while cranking engine. If test light blinks, go to step 20 . If test light does not blink, go to step 21.
15. Remove spark plugs from cylinders associated with misfire. Visually inspect spark plug electrodes for excessive fouling. Repair cause of misfire or replace fouled spark plugs. After repairs, go to next step.
16. Check spark plugs for carbon tracking, cracked or other damage to insulator. Check for spark plug electrode damage or incorrect gap. If carbon tracking is apparent on any of spark plugs, replace affected spark plugs and associated ignition wires. Repair as necessary. After repairs, go to step 22 . If no problems were found, go to next step.
17. Reinstall spark plug. Check engine for any mechanical problems. Repair as necessary. After repairs, go to step 22 . If no problems were found, go to next step.
18. If condition occurs while driving, inspect transmission torque converter clutch for problems. See appropriate OVERHAUL article in AUTOMATIC TRANSMISSIONS. Repair as necessary. After repairs, go to step 22 . If no problems were found, go to next step.
19. Inspect fuel system for contaminants. Repair as necessary. After repairs, go to step 22 . If no problems were found, see «DIAGNOSTIC AIDS»(ref-9296-S13035194642000101600000) .
20. Reinstall fuel injector fuse. Replace ignition coils associated with misfiring cylinders. After replacing ignition coil(s), go to step 22 .
21. Reinstall fuel injector fuse. Replace ignition control module. After replacing module, go to next step.
22. Review and record FREEZE FRAME data. Clear DTCs. Operate vehicle within conditions for setting this DTC. Using scan tool, monitor Misfire Current Cyl # display for each cylinder. If Misfire Current Cyl # display is incrementing for any cylinder (indicating a misfire currently occurring), go to step 2 . If Misfire Current Cyl # display is not incrementing for any cylinder, system okay.

Check secondary ignition wires. Check for damaged or faulty ignition coil. Substitute a known-good ignition coil. Check system grounds. Check MAF sensor, air induction system, fuel pressure, injectors, and EGR valve.

Extended idle periods or short trip driving could leave deposits on HO2S. Deposits could cause HO2S to respond slowly, affecting fuel control and causing misfire at idle.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. If engine knock can be heard, repair engine mechanical problem before proceeding with test. Operate vehicle within conditions required to set DTC. Using scan tool, select DTC, SPECIFIC function and enter this DTC. If scan tool indicates that this DTC failed this ignition, go to step 4 . If scan tool does not indicate that this DTC failed this ignition, go to next step.
3. Turn ignition on, engine off. Read and record FAILURE RECORDS data for DTC P0325. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S20992245002000101600000) .
4. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
5. Using scan tool, read and record FAILURE RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P0325. Monitor scan tool until DTC P0325 test runs. If scan tool indicates that this DTC failed this ignition, repeat step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connection at PCM. Check KS connector for proper connection or damage.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Operate vehicle within conditions required to set DTC. Using scan tool, select DTC, SPECIFIC function. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S15418783322000101600000) .
3. Using scan tool, monitor 24X crank sensor and CAM signal. If both the 24X signal and/or CAM signal is present, go to next step. If 24X crank sensor signal is present, see «DTC P0336: CRANKSHAFT POSITION SENSOR CIRCUIT PERFORMANCE»(ref-9296-S17712058612000101600000) .
4. Turn ignition on, engine off. Read and record FAILURE RECORDS data for DTC P0327. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S15418783322000101600000) .
5. Turn ignition off. Disconnect PCM and KS harness connectors. Check KS signal circuit between PCM and KS harness connector for open, short to voltage or short to ground. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to next step.
6. Check KS signal circuit for poor terminal connection at KS. Repair as necessary. After repairs, go to step 8 . If connection is okay, go to next step.
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Read and record FAILURE RECORDS data for DTC P0327. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, repeat step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connection at PCM or KS. Ensure KS harness is not routed too close to high-voltage wires, such as spark plug cables, ignition coils or other high-voltage components.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Operate vehicle within Fail Record conditions. Using scan tool, monitor specific DTC info for this DTC until DTC P0336 test runs. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S40987852702000101600000) .
3. Start engine. Using scan tool, observe 24X RPM. If 24X RPM vary with engine speed up to about 1600 RPM, see «DIAGNOSTIC AIDS»(ref-9296-S40987852702000101600000) . If 24X RPM does not vary with engine speed up to about 1600 RPM, go to next step.
4. Turn ignition off. Disconnect 24X CKP sensor harness connector. Turn ignition on, with engine off. Using a DVOM, check voltage between ground and ignition feed circuit of 24X sensor. If battery voltage is present, go to step 6 . If battery voltage is not present, go to next step.
5. Turn ignition off. Disconnect PCM harness. Check for short to ground or open circuit in 24X CKP sensor ignition feed circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 12 .
6. Using a test light connected to battery positive voltage, probe the 24X CKP sensor ground circuit. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
7. Turn ignition off. Disconnect PCM harness connector. Check for open in 24X CKP sensor ground circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 12 .
8. Using scan tool, monitor 24X RPM. Using fused jumper wire connected to battery positive voltage, momentarily touch the 24X CKP sensor signal circuit 5 times for about one second each. If 24X RPM changes each time the signal circuit is touched, go to step 14 . If 24X RPM does not change when signal circuit is touched, go to next step.
9. Check fuse in jumper wire. If fuse blew, go to step 11 . If fuse is okay, go to next step.
10. Check for short to voltage or open circuit in 24X CKP sensor signal circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 12 .
11. Check for short to ground in 24X CKP sensor signal circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to next step.
12. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to next step.
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 16 .
14. Check for poor connections at 24X CKP sensor. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to next step.
15. Replace 24X CKP sensor. After replacing sensor, go to next step.
16. Using scan tool, clear DTCs. Operate vehicle within Fail Record conditions. Recheck for DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness.

Check for faulty connections or damaged harness. Observe a voltmeter connected to 24X CKP sensor reference circuit at PCM harness connector while moving all related harness and connectors. A change in voltage indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Operate vehicle within Fail Record conditions. Using a scan tool, monitor specific DTC INFO for this DTC until DTC test runs. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S00813887542000101600000) .
3. Start engine. Using scan tool, observe cam signal. If cam signal is present, see «DIAGNOSTIC AIDS»(ref-9296-S00813887542000101600000) . If cam signal is not present, go to next step.
4. Turn ignition off. Disconnect CMP sensor harness connector. Turn ignition on, with engine off. Using a DVOM, check voltage between ground and CMP sensor harness connector ignition feed circuit. If voltage reading is about battery voltage, go to step 6 . If voltage reading is not about battery voltage, go to next step.
5. Turn ignition off. Disconnect PCM harness connector. Check for short to ground or open circuit in CMP sensor feed circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 12 .
6. Connect test light to battery voltage. Touch test light to CMP sensor ground circuit. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
7. Turn ignition off. Disconnect PCM harness connector. Check for open in CMP sensor ground circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 12 .
8. Start engine. Using scan tool, monitor cam signal. Using a fused jumper wire connected to battery voltage, momentarily touch jumper to the signal circuit 5 times for a duration of one second each. If cam signal changes each time the signal circuit is touched, go to step 14 . If cam signal does not change each time the signal circuit is touched, go to next step.
9. Check fuse in jumper wire. If fuse blew, go to step 11 . If fuse did not blow, go to next step.
10. Check for short to voltage or open circuit in CMP sensor signal circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 12 .
11. Check for short to ground in CMP sensor signal circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to next step.
12. Check for poor connections at PCM connector. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to next step.
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 16 .
14. Check for poor connections at CMP sensor. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to next step.
15. Replace CMP sensor. After replacing sensor, go to next step.
16. Using scan tool, clear DTCs. Operate vehicle within the Fail Record conditions. Recheck for DTCs. If DTC resets, go to step 2 . If DTC does not reset, system is okay.

Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness.

Check for faulty connections or damaged harness. Observe a voltmeter connected to CMP sensor signal circuit at PCM harness connector while moving all related harness and connectors. A change in voltage indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Inspect exhaust system for modifications or leaks. If a problem is found, repair as necessary and go to step 5 . If no problem is found, go to next step.
3. Remove EGR valve and check pintle, valve and passages and adapter for excessive deposits or restriction. Check EGR valve gasket and pipes for leaks. If a problem is found, repair as necessary. After repairs, go to step 5 . If no problem is found, go to next step.
4. Remove EGR inlet and outlet pipes from exhaust and intake manifolds. Inspect manifold EGR ports and pipes for blockage or damage. Repair as necessary. After repairs, go to next step. If no problem is found, see «DIAGNOSTIC AIDS»(ref-9296-S18329817512000101600000) .
5. Read and record FAILURE RECORDS data for DTC P0401. Clear DTCs and monitor EGR TEST COUNT while operating vehicle within conditions noted in DIAGNOSTIC AIDS until 9-12 test samples have been taken. Read SPECIFIC DTC. If scan tool indicates that DTC P0401 TEST RAN AND PASSED, repair is complete. If scan tool does not indicate that DTC P0401 TEST RAN AND PASSED, return to step 2 .

PCM will only run EGR flow test during gradual deceleration, a closed throttle condition and with vehicle speed greater than 20 MPH. Accelerate vehicle to greater than 20 MPH, and gradually decelerate 9-13 times.

Check for faulty connections or damaged harness. Inspect PCM harness connector EGR control circuit for backed-out terminal. Observe ACTUAL EGR POSITION display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

If EGR valve shows signs of excessive heat, check exhaust system for blockage or plugged catalytic converter.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command EGR from zero to 10 percent. If solenoid turns on and off with each command, see «DIAGNOSTIC AIDS»(ref-9296-S01367203052000101600000) . If solenoid does not turn on and off with each command, go to next step.
3. Turn ignition off. Disconnect EGR harness connector. Turn ignition off, with engine off. Using a test light connected to ground, probe EGR solenoid control circuit. Using scan tool, command EGR between zero and 10 percent. If test light turns on and off with each command, go to next step. If test light does not turn on and off with each command, go to step 5 .
4. Connect test light between EGR solenoid control and ground circuits. Using scan tool, command EGR between zero and 10 percent. If test light turns on and off with each command, go to step 8 . If test light does not turn on and off with each command, go to step 10 .
5. If test lamp remains illuminated with each command, go to step 7 . If test light does not remain illuminated with each command, go to next step.
6. Check for short to ground or open in EGR solenoid control circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check for short to voltage in EGR solenoid control circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for poor connections at EGR solenoid connector. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for poor connections at PCM connector. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair EGR solenoid ground circuit. After repairs, go to step 13 .
11. Replace EGR valve. After replacing EGR valve, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing ECM, go to next step.
13. Using scan tool, clear DTCs. Operate vehicle within conditions for setting this DTC. Recheck for DTCs. If DTC resets, go to step 2 . If DTC does not reset, system is okay.

Check for poor connection at PCM or EGR valve harness connectors.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, check if DTC P0403 or P0405 is present. If any of this DTC is present, diagnose affected DTC first. If DTC P0403 or P0405 is not present, select EGR OUTPUT CONTROL function. Increment EGR valve through all positions while comparing desired to actual EGR position. If desired and actual EGR position remains close to each other at all commanded positions, go to next step. If desired and actual EGR position is not within range, go to step 4 .
3. Using scan tool, review FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions and monitor SPECIFIC DTC info. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed in this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S39491997912000101600000) .
4. Disconnect EGR valve harness connector. Check voltage between EGR pintle position sensor ground circuit and 5-volt reference circuit at EGR harness connector. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step 10 .
5. Using test light connected to battery voltage, probe EGR pintle position signal circuit at EGR harness connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
6. Using a fused jumper wire, jumper EGR 5-volt reference circuit and EGR pintle position signal circuit at EGR harness connector. Using scan tool, observe actual EGR position. If actual EGR position is 100 percent, go to step 9 . If actual EGR position is not 100 percent, go to next step.
7. Turn ignition off. Disconnect PCM harness connector. Check for open in EGR pintle position signal circuit. Repair as necessary. After repairs, go to step 17 . If circuit is okay, go to step 15 .
8. Turn ignition off. Disconnect PCM harness connector. Using a test light connected to battery voltage, probe EGR pintle position signal circuit. If test light illuminates, go to step 13 . If test light does not illuminate, go to step 14 .
9. Check for poor terminal connections at EGR valve. Repair as necessary. After repairs, go to step 17 . If terminal connections are okay, go to step 12 .
10. Check 5-volt reference circuit for open between EGR and PCM. Check 5-volt reference circuit for short to ground. Repair as necessary. After repairs, go to step 17 . If circuits are okay, go to next step.
11. Check EGR pintle position ground sensor circuit for open or short to voltage. Repair as necessary. After repairs, go to step 17 . If circuit is okay, go to step 15 .
12. Replace EGR valve. After replacing EGR valve, go to step 17 .
13. Locate and repair short to ground in EGR pintle position signal circuit. After repairs, go to step 17 .
14. Check for short in EGR pintle position signal circuit to sensor ground. Repair as necessary. After repairs, go to step 17 . If circuit is okay, go to step 16 .
15. Check circuits related to EGR valve for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 17 . If circuits are okay, go to next step.
16. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
17. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0404. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, test is complete. If scan tool did not indicate that this test ran and passed, repeat step 2 .

Check for excessive deposits on EGR valve pintle or seat. Check for poor connection at PCM or EGR valve harness connectors.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, select EGR OUTPUT CONTROL function. Increment EGR valve through all positions while comparing desired to actual EGR position. If desired and actual EGR position remains close to each other at all commanded positions, go to next step. If desired and actual EGR position is not within range, go to step 4 .
3. Using scan tool, review FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions and monitor SPECIFIC DTC info. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed in this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S10031396212000101900000) .
4. Disconnect EGR valve harness connector. Check voltage between EGR pintle position sensor ground circuit and 5-volt reference circuit at EGR harness connector. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step 9 .
5. Using test light connected to battery voltage, probe EGR pintle position signal circuit at EGR harness connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
6. Using a fused jumper wire, jumper EGR 5-volt reference circuit and EGR pintle position signal circuit at EGR harness connector. Using scan tool, observe actual EGR position. If actual EGR position is 100 percent, go to step 13 . If actual EGR position is not 100 percent, go to next step.
7. Turn ignition off. Disconnect PCM harness connector. Check for open in EGR pintle position signal circuit. Repair as necessary. After repairs, go to step 19 . If circuit is okay, go to step 17 .
8. Turn ignition off. Disconnect PCM harness connector. Using a test light connected to battery voltage, probe EGR pintle position signal circuit. If test light illuminates, go to step 12 . If test light does not illuminate, go to step 15 .
9. Using test light connected to battery voltage, probe EGR 5-volt reference circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 .
10. Turn ignition off. Disconnect PCM harness connector. Using test light connected to battery voltage, probe EGR 5-volt reference circuit. If test light illuminates, go to step 16 . If test light does not illuminate, go to step 18 .
11. Check for open in 5-volt reference circuit between EGR and PCM. Repair as necessary. After repairs, go to step 19 . If circuits are okay, go to step 17 .
12. Locate and repair short to ground in EGR valve pintle position circuit. After repairs, go to step 19 .
13. Check for poor terminal connections at EGR valve. Check for short in EGR pintle position signal circuit to control circuit. Repair as necessary. After repairs, go to step 19 . If circuits are okay, go to next step.
14. Replace EGR valve. After replacing EGR valve, go to step 19 .
15. Check for short in EGR pintle position signal circuit to sensor ground. Repair as necessary. After repairs, go to step 19 . If circuit is okay, go to step 18 .
16. Locate and repair short to ground in 5-volt reference circuit. After repairs, go to step 19 .
17. Check circuits related to EGR valve for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 19 . If circuits are okay, go to next step.
18. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
19. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0404. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, repeat step 2 .

Check for excessive deposits on EGR valve pintle or seat. Check for poor connection at PCM or EGR valve harness connectors.

A Secondary Air Injection (AIR) pump is used lower tailpipe emissions on start-up. PCM grounds the AIR pump relay control circuit, which energizes the AIR pump. PCM also grounds the AIR combination valve vacuum control circuit, which energizes the AIR vacuum solenoid valve. Vacuum is then applied to both AIR combination valve diaphragms which open the shut-off valves. PCM enables both circuits simultaneously when AIR system operation is desired. When AIR system is active, the AIR pump forces fresh air into exhaust stream in order to accelerate catalyst operation. The AIR solenoid valves replace the conventional check valves. When AIR system is inactive, the shut-off valves prevent air flow in either direction. DTC will set if an air flow problem is detected.

DTC will set when the pre-catalyst HO2S voltage remains greater than 300 mV (passive) or 150 mV (active) for a calibrated period of time and the Short Term FT does not increase a calibrated amount during the test, and both conditions exist for 3 consecutive tests.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Check if DTC P0412 or P0418 is set. Diagnose affected DTC(s). If DTC P0412 or P0418 is not set, go to next step.
3. Check AIR pump relay switch feed fuse, located in underhood fuse block. If fuse is okay, go to next step. If fuse is blown, go to step 13 .
4. Using scan tool, command AIR pump on and off. If AIR pump turns on and off with each command, go to step 10 . If AIR pump does not turn on and off with each command, go to next step.
5. Observe AIR pump operation. If AIR pump runs continuously, go to step 16 . If AIR pump does not run continuously, go to next step.
6. Disconnect AIR pump relay. Using a test light connected to ground, probe relay switch feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 17 .
7. Using a fused jumper wire, jumper relay switch feed circuit to AIR pump feed circuit. If AIR pump operates, go to step 25 . If AIR pump does not operate, go to next step.
8. Leave the fused jumper wire in place. Disconnect AIR pump harness connector. Using test light connected to ground, probe AIR pump feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 18 .
9. Connect a test light between AIR pump feed and ground circuit. If test light illuminates, go to step 27 . If test light does not illuminate, go to step 19 .
10. Disconnect AIR hose/pipe from AIR pump. Using scan tool, command AIR pump on. If air flow is present at AIR pump outlet, go to next step. If air flow is not present at AIR pump outlet, go to step 28 .
11. Reconnect AIR hose/pipe to AIR pump. Disconnect AIR hose/pipe from AIR combination valve. Using scan tool, command AIR pump on. If air flow is present at AIR hose/pipe outlet, go to next step. If air flow is not present at AIR hose/pipe outlet, go to step 22 .
12. Start engine, check for vacuum at AIR combination valve. If vacuum is not present, check for damaged, pinched or disconnected vacuum line, a blocked/restricted vacuum port or a faulty vacuum control solenoid valve. Check for damaged, pinched or disconnected vacuum line between vacuum control solenoid and actuator diaphragm. Repair as necessary. After repairs, go to step 23 . If no problems were found, go to step 26 .
13. Disconnect AIR pump relay. Check relay feed circuit for short to ground. Repair as necessary. After repairs, go to step 20 . If circuit is okay, go to next step.
14. Disconnect AIR pump. Check AIR pump feed circuit for short to ground. Repair as necessary. After repairs, go to step 21 . If circuit is okay, go to next step.
15. Reconnect AIR relay and AIR pump. Replace fuse. Using scan tool, command AIR pump on. Check fuse. If fuse blows, go to step 28 . If fuse does not blow, see «DIAGNOSTIC AIDS»(ref-9296-S39816426892000101800000) .
16. Disconnect AIR pump relay. Observe AIR pump operation. If pump is still running, go to step 24 . If pump stops running, go to step 25 .
17. Repair open relay switch feed circuit. After repairs, go to step 29 .
18. Check for an open in AIR pump feed circuit. Repair as necessary. After repairs, go to step 29 . If circuit is okay, go to step 25 .
19. Repair open/high resistance in AIR pump ground circuit. After repairs, go to step 29 .
20. Repair short to ground in relay switch feed circuit. After repairs, go to step 29 .
21. Repair short to ground in AIR pump feed circuit. After repairs, go to step 29 .
22. Check for blocked or damaged combination valve. Check for restriction, blockage, disconnected or other damage to AIR hoses/pipes from combination valve to exhaust system. Repair as necessary. After repairs, go to step 29 .
23. Repair the vacuum system as necessary. After repairs, go to step 29 .
24. Repair short to voltage in AIR pump feed circuit. After repairs, go to step 29 .
25. Replace AIR pump relay. After replacing relay, go to step 29 .
26. Replace affected AIR combination valve. After replacing combination valve, go to step 29 .
27. Check for poor connections at AIR pump. Repair as necessary. After repairs, go to step 29 . If connections are okay, go to next step.
28. Replace AIR pump. After replacing AIR pump, go to step 29 .
29. Using scan tool, clear DTCs. Turn ignition off and wait 15 seconds. Operate vehicle within conditions required for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
30. Using scan tool, review CAPTURED INFO. Recheck for DTCs. If any other DTC(s) are set, diagnose affected DTC(s). If no DTC(s) are set, system is okay.

Check for faulty connections or damaged harness. Inspect PCM harness connector EGR control circuit for backed-out terminal. Observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

An AIR pump is used to lower tailpipe emissions on start-up. PCM grounds the AIR pump relay control circuit, which energizes AIR pump. PCM also grounds the AIR combination valve vacuum control solenoid circuit, which energizes the AIR vacuum control solenoid. Vacuum is then applied to both AIR combination valve diaphragms which open the shut-off valves. PCM enables both circuits simultaneously when AIR system operation is desired. When AIR system is active, AIR pump forces fresh air into exhaust stream in order to accelerate catalyst operation. The AIR combination valves replace the conventional check valves. When AIR system is inactive the shut-off valves prevent air flow in either direction. DTC will set when there is a problem with AIR vacuum control solenoid circuit.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command AIR solenoid on and off. If solenoid turns on and off with each command, see «DIAGNOSTIC AIDS»(ref-9296-S10726516472000101800000) . If solenoid does not turn on and off with each command, go to next step.
3. Turn ignition off. Disconnect AIR solenoid harness connector. Turn ignition on, with engine off. Using a test light connected to ground, probe solenoid coil feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
4. Connect test light between solenoid control and coil feed circuit. Using scan tool, command AIR solenoid on and off. If test light turns on and off with each command, go to step 8 . If test light does not turn on and off with each command, go to next step.
5. If test light remains on with each command, go to step 7 . If test light does not remain on with each command, go to next step.
6. Check solenoid control circuit for short to voltage or an open circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check solenoid control circuit for short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for poor connections at solenoid. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair solenoid feed circuit. After repairs, go to step 13 .
11. Replace solenoid. After replacing solenoid, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, clear DTCs. Operate vehicle within conditions for setting this DTC. Recheck for DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Note. DO NOT operate AIR pump for longer than 60 seconds. Continuous operation of AIR pump will damage pump.

Remove any debris from connector surfaces before servicing a component. Inspect connector gaskets when diagnosing or replacing a component. Ensure that gaskets are installed correctly.

Check for faulty connections or damaged harness. Inspect PCM harness connector EGR control circuit for backed-out terminal. Observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Ignition voltage is supplied directly to AIR pump relay. PCM controls relay by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM. When PCM is commanding a component on, voltage of control circuit should be low (about zero volts). When PCM is commanding control circuit to a component off, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, this DTC will set.

DTC will also set when a short to ground, an open circuit or a short to battery voltage is detected on the control circuit, and condition is present for at least 30 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command AIR pump relay and solenoid on and off. If solenoid turns on and off with each command, see «DIAGNOSTIC AIDS»(ref-9296-S35991922212000101800000) . If solenoid does not turn on and off with each command, go to next step.
3. Turn ignition off. Disconnect AIR relay. Turn ignition on, with engine off. Using a test light connected to ground, probe relay coil feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
4. Connect test light between relay control and coil feed circuit. Using scan tool, command AIR pump relay and solenoid on and off. If test light turns on and off with each command, go to step 8 . If test light does not turn on and off with each command, go to next step.
5. If test light remains on with each command, go to step 7 . If test light does not remain on with each command, go to next step.
6. Check relay control circuit for short to voltage or an open circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check relay control circuit for short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for poor connections at relay. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for poor connections at PCM. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair relay feed circuit. After repairs, go to step 13 .
11. Replace relay. After replacing relay, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, clear DTCs. Operate vehicle within conditions for setting this DTC. Recheck for DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Note. DO NOT operate AIR pump for longer than 60 seconds. Continuous operation of AIR pump will damage pump.

Remove any debris from connector surfaces before servicing a component. Inspect connector gaskets when diagnosing or replacing a component. Ensure that gaskets are installed correctly.

Check for faulty connections or damaged harness. Inspect PCM harness connector EGR control circuit for backed-out terminal. Observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

Three-Way Catalyst (TWC) system is used to control emission. PCM uses signal from Heated Oxygen Sensors (HO2S) to read efficiency of TWC. DTC will set if TWC oxygen storage capacity is less than a predetermined threshold.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Diagnose any other DTCs before proceeding. If no other DTCs are set, go to next step.
3. Using scan tool, clear DTCs. Ensure A/C is off. Warm engine to normal operating temperature. Operate vehicle within the conditions for setting this DTC. Test may need to be performed up to 6 times in order to pass or fail. If test has been performed or attempted for more than 6 times and DTC has not passed or failed this ignition cycle, test may be aborting. See «DIAGNOSTIC AIDS»(ref-9296-S01153055672000101600000) . If scan tool indicates that DTC ran and passed in this ignition cycle, system is okay. If scan tool does not indicate that DTC ran and passed in this ignition cycle, go to next step.
4. Ensure TWC is an original equipment part. Check TWC for dents or discoloration caused by excessive heat. Ensure no internal damaged catalyst rattle exists. If a problem is found, repair as necessary. After repairs, go to step 9 . If no problem is found, go to next step.
5. Check exhaust system for leaks, damage, loose or missing hardware. If a problem is found, repair as necessary. After repairs, go to step 7 . If no problems are found, go to next step.
6. Ensure HO2S 2 is securely installed and that harness is not damaged or contacting exhaust. If a problem is found, repair as necessary. After repairs, go to step 8 . If no problems are found, go to step 9 .
7. Repair exhaust system. After repairs, go to step 10 .
8. Repair HO2S sensor circuit. After repairs, go to step 10 .
9. Replace TWC. Check for possible engine misfire DTC or engine mechanical problem. After repairs, go to next step.
10. Using scan tool, clear DTCs. Ensure A/C is off. Start and warm engine to normal operating temperature. Operate vehicle within the conditions for setting this DTC. Test may need to be performed up to 6 times in order to pass or fail. If test has been performed or attempted for more than 6 times and DTC has not passed or failed this ignition cycle, test may be aborting. See «DIAGNOSTIC AIDS»(ref-9296-S01153055672000101600000) . If scan tool indicates that DTC ran and passed in this ignition cycle, go to next step. If scan tool does not indicate that DTC ran and passed in this ignition cycle, repeat step 2 .
11. If additional DTCs are present, diagnose affected DTCs. If no additional DTCs are present, system okay.

PCM will not enable the catalyst test if

1. Engine speed is plus or minus 100 RPM from desired idle speed.
2. TP is zero percent.
3. Short term integrator is between -20 percent and +20 percent.

The catalyst test will abort if vehicle falls out of following the conditions

1. Engine speed is plus or minus 125 RPM from desired idle speed.
2. TP is zero percent.
3. Short term integrator is between -20 percent and +20 percent.

The catalyst test may abort due to change in engine load (i.e., A/C, cooling fan on). If this problem occurs, use scan tool to force cooling fans to turn on, then repeat test.

Check for faulty connections or damaged harness. Inspect PCM harness connector EGR control circuit for backed-out terminal. Observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Check for any other DTCs set. If other DTC(s) are set, diagnose affected DTC(s). If no other DTC(s) are set, go to next step.
3. Check EVAP system for loose, incorrect, defective or missing fuel filler cap. Check for improperly routed, kinked or damaged EVAP system purge or vapor pipes. Check for damaged EVAP system component(s). Check for loose, missing or damaged service port dust cap and/or Schrader valve. Repair or replace as necessary. After repairs, go to step 23 . If no problems were found, go to next step.
4. Turn ignition on, with engine off. Using scan tool, observe the fuel tank pressure parameter. If scan tool indicates that fuel tank pressure is about zero inch H2O, go to next step. If scan tool does not indicate fuel tank pressure at about zero inch H2O, diagnose using DTC P0453. See «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE»(ref-9296-S37201718012000101600000) .
5. Install Filler Tank Cap Adaptor (J-41415-40 ) to fuel filler neck and fuel filler cap. Connect EVAP Pressure/Purge Diagnostic Station (J-41413) to fuel tank cap adaptor. Using scan tool, capture Fail Records data for this DTC and clear the DTC. Select seal option to seal EVAP system. Attempt to pressurize system to 5 in. H2O by slowly turning EVAP service station rotary switch to PRESSURE position. If pressure is achieved, go to next step. If pressure is not achieved, go to step 11 .
6. Use EVAP service station to maintain fuel tank pressure at specified value. Using scan tool, observe fuel tank pressure parameter. If scan tool indicates fuel tank pressure at 5 in. H2O, go to next step. If scan tool does not indicate fuel tank pressure at 5 in. H2O, go to «DTC P0452: FUEL TANK PRESSURE SENSOR CIRCUIT - LOW VOLTAGE»(ref-9296-S03292711752000101600000) .
7. Using EVAP station, maintain fuel tank pressure at 5 in. H2O. Using scan tool, increase purge to 100 percent to relieve system pressure. If fuel tank pressure decreased to about zero in. H2O, see «DIAGNOSTIC AIDS»(ref-9296-S17263825912000101600000) . If fuel tank pressure did not decrease to about zero in. H2O, go to next step.
8. Disconnect purge pipe from EVAP purge valve. Observe fuel tank pressure reading on scan tool. If fuel tank pressure is zero in. H2O, go to step 16 . If fuel tank pressure is not zero in. H2O, go to next step.
9. Disconnect EVAP canister purge pipe. Observe fuel tank pressure reading on scan tool. If fuel tank pressure is zero in. H2O, go to step 17 . If fuel tank pressure is not zero in. H2O, go to next step.
10. Disconnect EVAP canister vapor pipe. Observe fuel tank pressure reading on scan tool. If fuel tank pressure is zero in. H2O, go to step 20 . If fuel tank pressure is not zero in. H2O, go to step 18 .
11. Disconnect EVAP canister fuel tank vapor pipe and EVAP purge pipe. Block canister port for fuel tank vapor line. Using scan tool, seal EVAP system. Connect a hand-held vacuum pump to EVAP canister port and apply 5 in. Hg vacuum. If vacuum holds, go to step 14 . If vacuum will not hold, go to next step.
12. Disconnect EVAP vent hose from EVAP vent valve. Plug vent hose. Using a hand-held vacuum pump, apply 5 in. Hg vacuum. If vacuum holds, go to step 22 . If vacuum does not hold, go to next step.
13. Disconnect EVAP vent hose from EVAP canister. Plug vent hose port. Using a hand-held vacuum pump, apply 5 in. Hg vacuum. If vacuum holds, go to step 19 . If vacuum does not hold, go to step 20 .
14. Disconnect engine vacuum purge line from EVAP canister purge valve. Using EVAP diagnostic station, connect vacuum gauge hose to canister side of purge valve. Turn ignition on, with engine off. Using scan tool, select seal option to seal EVAP system. Start engine. Operate engine from 1200-1500 RPM and observe vacuum level. If EVAP diagnostic station vacuum gauge indicates zero in. Hg, go to next step. If vacuum gauge does not indicate zero in. Hg, go to step 21 .
15. Reconnect all EVAP hardware that was previously disconnected. Turn ignition on, with engine off. Using scan tool, seal EVAP system. Use EVAP diagnostic station to continuously attempt to pressurize EVAP system to 5 in. H2O. Using an Ultrasonic Leak Detector (J-41416), locate leaks in fuel sender "O" ring, fuel tank, fuel tank relief valve, EVAP pipes/hoses, fuel cap, and fuel fill neck and seal. Repair as necessary. After repairs, go to step 23 .
16. Check for blocked or restricted vacuum source to EVAP purge valve. Repair as necessary. After repairs, go to step 23 . If no problem is found, go to step 21 .
17. Repair plugged EVAP purge pipe. After repairs, go to step 23 .
18. Repair plugged EVAP vapor pipe. After repairs, go to step 23 .
19. Replace fresh air vent hose. After replacing vent hose, go to step 23 .
20. Replace EVAP canister. After replacing EVAP canister, go to step 23 .
21. Replace EVAP canister purge valve. After replacing purge valve, go to step 23 .
22. Replace EVAP vent valve. After replacing vent valve, go to step 23 .
23. Reconnect all previously disconnected hardware. Turn ignition on, with engine off. Using scan tool, seal EVAP system. Using EVAP diagnostic station, pressurize system to 15 in. Hg. Turn rotary switch on EVAP diagnostic station to OFF/HOLD position. If EVAP pressure decreases to less than 10 in. H2O within 2 minutes, go to step 3 . If EVAP pressure does not decrease to less than 10 in. Hg, system is okay.

Check for a malfunctioning or damage EVAP canister, a loose, missing, defective or incorrect fuel fill cap or an incorrectly routed, kinked, pinched, plugged, or defective EVAP system vacuum and vapor pipes. Check for charcoal release from EVAP canister. Remove any debris from connector surfaces before servicing a component. Check connector gaskets when diagnosing or replacing a component. Ensure gaskets are installed correctly.

Check for poor terminal connections, backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Observe scan tool display while moving connectors and wiring harnesses related to the sensor. A change in scan tool display may indicate the location of fault. Ensure PCM and engine grounds are clean and secured.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Check if any other DTCs are set. Diagnose affected DTC(s). If no other DTC(s) are set, go to next step.
3. Check for improperly routed, kinked or damaged EVAP system purge or vapor lines. Check for loose, incorrect or defective fuel filler cap. Check for loose, missing or damaged service port dust cap and/or Schrader valve. Check for damaged EVAP system component(s). Repair as necessary. After repairs, go to step 14 . If no problems were found, go to next step.
4. Turn ignition on, with engine off. Using scan tool, observe fuel tank pressure parameter. If fuel tank pressure is about zero in. H2O, go to next step. If fuel tank pressure is not about zero in. H2O, go to «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE»(ref-9296-S37201718012000101600000) .
5. Install Fuel Tank Cap Adaptor (J-41415-40) to fuel filler neck and fuel filler cap. Connect EVAP Pressure/Purge Diagnostic Station (J-41413) to fuel tank cap adaptor. Turn ignition on, with engine off. Using scan tool, capture FAILURE RECORD data for this DTC and clear DTCs. Select seal option to seal EVAP system. Attempt to pressurize system to 5 in. H2O by slowly turning EVAP diagnostic station rotary switch to PRESSURE position. Observe scan tool. If fuel tank pressure is about 5 in. H2O, go to next step. If fuel tank pressure is not about 5 in. H2O, go to «DTC P0452: FUEL TANK PRESSURE SENSOR CIRCUIT - LOW VOLTAGE»(ref-9296-S03292711752000101600000) .
6. Using scan tool, perform SERVICE BAY TEST for EVAP system. If scan tool indicates that system passed the test, see «DIAGNOSTIC AIDS»(ref-9296-S27072489652000101600000) . If scan tool does not indicate that the system passed the test, go to next step.
7. Disconnect fuel tank vapor line and EVAP purge line from EVAP canister. Block canister fitting for fuel tank pressure line. Connect a hand-held vacuum pump to canister fitting for EVAP purge line. Ensure that EVAP vent solenoid is still commanded on. Apply vacuum to EVAP canister. If vacuum can be maintained at 5 in. Hg, go to step 10 . If vacuum cannot be maintained at 5 in. Hg, go to next step.
8. Disconnect vent hose from vent valve and plug vent hose. Using a hand-held vacuum pump, apply 5 in. Hg vacuum. If vacuum can be maintained, go to next step. If vacuum cannot be maintained, go to step 13 .
9. Disconnect vent hose from EVAP canister and plug vent port. Apply 5 in. Hg vacuum. If vacuum can be maintained, go to step 11 . If vacuum cannot be maintained, go to step 12 .
10. Reconnect all previously disconnected hardware. Using scan tool, seal EVAP system. Using EVAP service diagnostic station, pressurize EVAP system to 15 in. Hg. Using Ultrasonic Leak Detector (J-41416), locate leaks in fuel sender "O" ring, fuel tank, fuel tank relief valve, EVAP pipes/hoses, filler cap, and fuel filler neck and seal. Repair as necessary. After repairs, go to step 14 .
11. Replace EVAP canister. After replacing EVAP canister, go to step 14 .
12. Replace EVAP fresh air hose. After replacing hose, go to step 14 .
13. Replace EVAP vent valve. After replacing vent valve, go to next step.
14. Reconnect all EVAP hardware that was previously disconnected. Turn ignition on, with engine off. Using scan tool, select seal EVAP system. Using EVAP diagnostic station, pressurize system to 15 in. Hg. Move rotary switch in diagnostic station to OFF/HOLD position and observe EVAP pressure gauge. If EVAP pressure decreases to less than 10 in. Hg within 2 minutes, repeat step 3 . If EVAP pressure does not decrease to less than 10 in. Hg, system is okay.

Check for the following

1. Cranked and punctured EVAP canister.
2. Damaged or disconnected source vacuum line, EVAP purge line, vent hose, for fuel tank vapor line.
3. Poor connection at PCM.
4. Inspect harness connectors for backed-out terminals, improper mating, broken lock, damaged terminals, or poor wire connection.
5. Check for intermittent in circuit.
6. Check for kinked, pinched or plugged vacuum lines to EVAP purge or fuel tank vapor line. Also check for restrictions.
7. Faulty or damaged evaporative canister.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, increase and decrease purge solenoid up and down. If solenoid responds as commanded, see «DIAGNOSTIC AIDS»(ref-9296-S17351912102000101600000) . If solenoid does not respond as commanded, go to next step.
3. Turn ignition off. Disconnect purge solenoid. Turn ignition on, with engine off. Using a test light connected to ground, probe purge solenoid ignition feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
4. Connect test light between purge solenoid ignition feed and ground circuits. Using scan tool, command purge solenoid on and off. If test light turns on and off, go to step 8 . If test light does not turn on and off, go to next step.
5. If test light remains illuminated, go to step 7 . If test light remains off, go to next step.
6. Check purge solenoid for an open or short to voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check purge solenoid control circuit for a short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for faulty purge solenoid connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for faulty PCM connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair purge solenoid ignition feed circuit. After repairs, go to step 13 .
11. Replace purge solenoid. After replacing solenoid, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, clear DTCs. Operate vehicle under conditions required to set DTC. Check for DTCs. If DTC resets, go to step 2 . If no DTCs are set, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Check for DTCs. If any other DTC(s) are set, diagnose affected DTC(s). If not other DTC(s) are set, go to next step.
3. Check EVAP system for damaged EVAP vent valve or pinched EVAP fresh air vent hose. Repair as necessary. After repairs, go to step 13 . If no problems were found, go to next step.
4. Turn ignition off. Disconnect EVAP canister line from fuel tank or EVAP canister to relieve fuel tank pressure. Turn ignition on, with engine off. Using scan tool, observe fuel tank pressure parameter. If fuel tank pressure is about zero in. H2O, go to next step. If fuel tank pressure is not about zero in. H2O, go to «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE»(ref-9296-S37201718012000101600000) .
5. Disconnect purge pipe from EVAP canister purge valve. Connect EVAP Pressure/Purge Diagnostic Station (J-41413) vacuum hose to purge valve. Using scan tool, seal EVAP system. Start engine and increase engine speed 1200-1500 RPM. If vacuum reading is zero in. H2O, go to next step. If vacuum reading is not zero in. H2O, go to step 11 .
6. Reconnect all previously disconnected hardware. Start and operate engine at idle. Using scan tool, seal EVAP vent valve. When purge is enabled, allow fuel tank pressure to reach 5 in. H2O. Using scan tool, open EVAP vent valve. If fuel tank pressure parameter is zero in. H2O, see «DIAGNOSTIC AIDS»(ref-9296-S24715413122000101600000) . If fuel tank pressure parameter is not zero in. H2O, go to next step.
7. Turn ignition off. Disconnect fuel tank vapor pipe and EVAP purge pipe from EVAP canister. Block vapor port on EVAP canister. Using a hand-held vacuum pump, apply 5 in. Hg to EVAP canister purge port. Disconnect fresh air vent hose from EVAP vent valve. If vacuum pump reading is 5 in. Hg, go to next step. If vacuum pump reading is not 5 in. Hg, go to step 9 .
8. Disconnect fresh air vent hose from EVAP canister. If vacuum pump indicates 5 in. Hg, go to step 10 . If vacuum pump does not indicate 5 in. Hg, go to step 12 .
9. Replace EVAP vent valve. After replacing vent valve, go to step 13 .
10. Replace EVAP canister. After replacing EVAP canister, go to step 13 .
11. Replace EVAP canister purge valve. After replacing EVAP canister purge valve, go to step 13 .
12. Repair blockage from fresh air vent hose. After repairs, go to next step.
13. Reconnect all EVAP previously disconnected hardware. Turn ignition on, with engine off. Using scan tool, command vent valve on (closed) to seal system. Using EVAP station, pressurize EVAP system to 5 in. Hg by slowly turning the rotary switch to PRESSURE position. Monitor EVAP diagnostic station pressure gauge. Turn EVAP diagnostic station rotary switch to OFF/HOLD position. Using scan tool, command EVAP vent valve off (open) to relieve system pressure. If pressure decreases to less than zero in. H2O within 2 minutes, go to step 3 . If pressure does not decrease to less than zero in. H2O within 2 minutes, system is okay.

Check for the following

1. Poor connection at PCM.
2. Inspect harness connectors for backed-out terminals, improper mating, broken lock, damaged terminals, or poor wire connection.
3. Check for intermittent, open or shorted circuit.
4. Check for kinked, pinched or plugged vent hose.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command vent solenoid on and off. If solenoid responds as commanded, see «DIAGNOSTIC AIDS»(ref-9296-S39444459062000101600000) . If solenoid does not respond as commanded, go to next step.
3. Turn ignition off. Disconnect vent solenoid harness connector. Turn ignition on, with engine off. Using a test light connected to ground, probe vent solenoid ignition feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
4. Connect test light between vent solenoid ignition feed and ground circuits. Using scan tool, command vent solenoid on and off. If test light turns on and off, go to step 8 . If test light does not turn on and off, go to next step.
5. If test light remains illuminated, go to step 7 . If test light remains off, go to next step.
6. Check vent solenoid control circuit for an open or short to voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check vent solenoid control circuit for a short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for faulty vent solenoid connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for faulty PCM connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair vent solenoid ignition feed circuit. After repairs, go to step 13 .
11. Replace vent solenoid. After replacing solenoid, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, clear DTCs. Operate vehicle under conditions required to set DTC. Check for DTCs. If this DTC resets, go to step 2 . If DTCs does not reset, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Monitor fuel tank pressure sensor voltage on scan tool. If scan tool reading is 0.30 volt or less, go to step 4 . If scan tool reading is not 0.30 volt or less, go to next step.
3. Turn ignition on, engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC and observe parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this DTC to run. Using scan tool, select DTC option, SPECIFIC DTC option, then enter this DTC. If scan tool indicates that this diagnostic failed this ignition cycle, go to next step. If scan tool does not indicate that this diagnostic failed this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S31013218232000101600000) .
4. Disconnect fuel tank pressure sensor connector. Jumper fuel tank pressure sensor 5-volt reference circuit and signal circuit at harness connector. Using scan tool observe fuel tank pressure sensor voltage. If scan tool display reads 5 volts, go to step 8 . If scan tool display does not read 5 volts, go to next step.
5. Check voltage between 5-volt reference voltage circuit and sensor ground circuit at fuel tank pressure sensor harness connector. If voltage reading is 5 volts, go to step 9 . If voltage reading is not 5 volts, go to next step.
6. Turn ignition off. Disconnect PCM harness connector. Check 5-volt reference circuit for poor connection at PCM connector. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to next step.
7. Check fuel tank pressure sensor 5-volt reference circuit between sensor and PCM for open, short to ground, or short to sensor ground circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 12 .
8. Check for poor terminal connections at fuel tank pressure sensor connector. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure signal circuit for poor connection at PCM connector. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to next step.
10. Check fuel tank pressure signal circuit between the fuel tank pressure sensor connector and PCM for an open, short to ground, or short to sensor ground circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 12 .
11. Replace fuel tank pressure sensor. After replacing sensor, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, repeat step 2 .

An intermittent open in the signal or 5-volt reference circuit or connectors will set DTC. Wiggle harnesses and connectors while monitoring tank pressure voltage. Review malfunction history data and attempt to reproduce the condition and fault.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Monitor fuel tank pressure sensor voltage on scan tool. If voltage reading is greater than 4.7 volts, go to step 4 . If voltage reading is not greater 4.7 volts, go to next step.
3. Turn ignition on, engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC and observe parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this DTC to run. Using scan tool, select DTC option, SPECIFIC DTC option, then enter this DTC. If scan tool indicates that this diagnostic failed this ignition cycle, go to next step. If scan tool does not indicate that this diagnostic failed this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S20013901332000101600000) .
4. Disconnect fuel tank pressure sensor connector. Using scan tool observe fuel tank pressure sensor voltage. If scan tool display reads about zero volts, go to step 6 . If scan tool display is not about zero volts, go to next step.
5. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure signal circuit for short to voltage or short to 5-volt reference circuit. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to step 10 .
6. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure ground circuit for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
7. Check for open in fuel tank pressure sensor ground circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to next step.
8. Check for poor terminal connections at fuel tank pressure sensor connector. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to next step.
9. Replace fuel tank pressure sensor. After replacing sensor, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step 2 .

Check for damaged harness or poor connection at PCM or fuel tank pressure sensor.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor. If value is within 3.5-98.0 percent, see «DIAGNOSTIC AIDS»(ref-9296-S32307711492000101600000) . If value is not within 3.5-98.0 percent, go to next step.
3. Disconnect fuel level sensor harness connector. Using scan tool, monitor fuel level sensor. If value is less than 3.5 percent, go to next step. If value is not less than 3.5 percent, go to step 6 .
4. Check fuel level sensor signal circuit for short to ground. Repair as necessary. After repairs, go to step 7 . If circuit is okay, go to step 6 .
5. Replace fuel level sensor. After replacing fuel level sensor, go to step 7 .
6. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
7. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting the DTC. If scan tool indicates that this diagnostic ran and passed, system is okay. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe fuel level parameter. If fuel level parameter is greater than 98 percent, go to next step. If fuel parameter is not greater than 98 percent, see «DIAGNOSTIC AIDS»(ref-9296-S05674672632000101600000) .
3. Disconnect pass-through connector located near fuel tank. Connect a fused jumper between fuel level sensor signal circuit and ground circuit at harness connector. If fuse in jumper wire blows, repair short to ground in circuit. If fuse is okay, observe fuel level parameter on scan tool. If fuel level parameter is less than 3.5 percent, go to step 6 . If fuel level parameter is not less than 3.5 percent, go to next step.
4. Check fuel level signal circuit for short to voltage, high resistance or open circuit. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to next step.
5. Check fuel level ground circuit for high resistance or open circuit. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to step 7 .
6. Check for poor connections at fuel level sensor harness connector. Repair as necessary. After repairs, go to step 10 . If connections are okay, go to step 8 .
7. Check fuel level sensor signal and ground circuit for poor connections at PCM connector. Repair as necessary. After repairs, go to step 10 . If connections are okay, go to step 9 .
8. Replace fuel level sensor. After replacing fuel level sensor, go to step 10 .
9. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
10. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting the DTC. If scan tool indicates that this diagnostic ran and passed, system is okay. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relay No. 1 on and off. If relay turns on and off, see «DIAGNOSTIC AIDS»(ref-9296-S34012867052000101600000) . If relay does not turn on and off, go to next step.
3. Turn ignition off. Remove relay. Turn ignition on, with engine off. Using a test light connected to ground, probe relay coil battery feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
4. Connect test light between relay coil battery feed circuit and relay control circuit. Using scan tool, command relay on and off. If test light turns on and off, go to step 8 . If test light does not turn on and off, go to next step.
5. If test light remains illuminated for each command, go to step 7 . If test light does not remain illuminated for each command, go to next step.
6. Check relay control circuit for an open or short to voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check relay control circuit for short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for faulty relay connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for faulty PCM harness connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair relay coil battery feed circuit. After repairs, go to step 13 .
11. Replace relay. After replacing relay, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relays No. 2 and 3 on and off. If both relays turn on after several seconds, and then turn off with each command, see «DIAGNOSTIC AIDS»(ref-9296-S19062545062000101600000) . If operation is not as specified, go to next step.
3. Turn ignition off. Disconnect relays No. 2 and 3. Turn ignition on, with engine off. Using a test light connected to ground, probe coil feed circuits for each relay. If test light illuminates for both circuits, go to next step. If test light does not illuminate for both circuits, go to step 10 .
4. Connect test light between control circuits of each relay and battery feed circuits of each relay. Using scan tool, command relays No. 2 and 3 on and off. If test light turns on after several seconds, and then turns off with each command on both relays, go to step 8 . If test light does not respond as specified, go to next step.
5. If test light remains illuminated with each command when probing either battery feed circuit, go to step 7 . If test light does not remain illuminated with each command when probing either battery feed circuit, go to next step.
6. Check control circuit of each relay for an open or short to voltage. Repair as necessary. After repairs, go to step 13 . If circuits are okay, go to step 9 .
7. Check control circuit of each relay for a short to ground. Repair as necessary. After repairs, go to step 13 . If circuits are okay, go to step 9 .
8. Check for faulty relay connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for faulty PCM harness connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair battery feed circuit to affected relay. After repairs, go to step 13 .
11. Replace affected relay. After replacing relay, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 650 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 50 RPM of desired RPM for each command, see «DIAGNOSTIC AIDS»(ref-9296-S07914298082000101600000) . If ENGINE SPEED is not as specified, to next step.
4. Disconnect IAC harness connector. Install IAC Noid Light (J-37027) in IAC harness connector. Monitor noid lights while commanding engine speed up to 1500 RPM, down to 650 RPM, and up to 1500 RPM. Both noid lights should cycle Green and Red, but not off as RPM changes from 650-1500 RPM. If lights flash as specified, go to step 6 . If lights do not flash as specified, go to next step.
5. Check IAC "A" high and low, and IAC "B" high and low circuits for open, short to voltage or short to ground. Repair as necessary. After repairs, go to step 11 . If circuits are okay, go to step 9 .
6. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
7. Check for faulty connection at IAC harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
8. Replace IAC valve. After replacing IAC valve, go to step 11 .
9. Check for faulty connection at PCM harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 100 RPM of desired RPM for each command, repair is complete. If ENGINE SPEED is not as specified, return to step 2 .

Check for faulty connection at IAC and PCM connectors. Check for damaged harness. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Check for large vacuum leak, such as incorrectly installed PCV valve or disconnected brake booster hose. Check for restricted air intake system.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, go to next step.
3. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 650 and then up to 1500 while monitoring engine speed display. If engine speed remains within 50 RPM of desired RPM for each RPM command, no problem is detected at this time. See «DIAGNOSTIC AIDS»(ref-9296-S37781064142000101600000) . If engine speed does not remain within 50 RPM of desired RPM for each RPM command, go to next step.
4. Disconnect IAC valve harness connector. Install IAC Noid Light (J-37027-A) to IAC valve harness connector. Using scan tool, command RPM up to 1500, down to 650 and then up to 1500 while monitoring engine speed display. If each noid light cycles Red and Green but never off, go to step 6 . If each noid light does not cycle Red and Green, go to next step.
5. Check for an open, short to voltage or short to ground in IAC valve related circuits between IAC valve and PCM. Repair as necessary. After repairs, go to step 11 . If circuits are okay, go to step 9 .
6. Check for vacuum leaks. Check for binding throttle plate or throttle shaft. Check for misadjusted throttle and cruise control cables. Check PCV system operation. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
7. Check for poor connection at IAC valve connector. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
8. Replace IAC valve. Alter replacing IAC valve, go to step 11 . If no problem is found, go to next step.
9. Check for poor connection at PCM valve connector. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 650 and then up to 1500 while monitoring ENGINE SPEED display. If engine speed remains within 50 RPM of desired RPM for each RPM command, repair is complete. See «DIAGNOSTIC AIDS»(ref-9296-S37781064142000101600000) . If engine speed does not remain within 50 RPM of desired RPM for each RPM command, repeat step 2 .

Inspect IAC valve connector for proper connection. Inspect throttle linkage for signs of binding or excessive wear. A slow or unstable idle may be caused by one of the following

1. Fuel system too rich or too lean.
2. Foreign material in throttle body bore or in air induction system.
3. Leaking or restricted intake manifold.
4. Excessive engine overloading.
5. Too high a viscosity engine oil.

Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe A/C pressure sensor parameter. If A/C pressure sensor parameter is within 0.1- 4.9 volts, see «DIAGNOSTIC AIDS»(ref-9296-S35444538792000101600000) . If A/C pressure sensor parameter is not within 0.1-4.9 volts, go to next step.
3. Turn ignition off. Disconnect A/C pressure sensor harness connector. Turn ignition on, with engine off. Using scan tool, observe A/C pressure sensor parameter. If A/C pressure sensor parameter is less than 0.1 volt, go to next step. If A/C pressure sensor parameter is not less than 0.1 volt, go to step 10 .
4. Turn ignition off. Connect a fused jumper wire between A/C pressure sensor 5-volt reference "B" circuit and signal circuit. Turn ignition on, with engine off. Using scan tool, observe A/C pressure sensor parameter. If A/C pressure sensor parameter is greater than 4.9 volts, go to next step. If A/C pressure sensor parameter is not greater than 4.9 volts, go to step 8 .
5. Disconnect fused jumper wire. Check voltage between A/C pressure sensor 5-volt reference "B" circuit and ground circuit. If voltage reading is less than 5.1 volts, go to next step. If voltage reading is not less than 5.1 volts, go to step 7 .
6. Turn ignition off. Check resistance between a known-good ground and A/C pressure sensor ground circuit. If resistance is less than 5 ohms, go to step 12 . If resistance is not less than 5 ohms, go to step 11 .
7. Check for short to voltage in A/C pressure sensor 5-volt reference "B" circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 13 .
8. Check A/C pressure sensor 5-volt reference "B" circuit for short to ground, high resistance, or open circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to next step.
9. Check A/C pressure sensor signal circuit for short to ground, high resistance, or an open circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 13 .
10. Check A/C pressure sensor signal circuit for short to voltage. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 13 .
11. Turn ignition off. Disconnect PCM harness connector. Check A/C pressure sensor ground circuit for high resistance or an open circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 13 .
12. Check for poor connections at A/C pressure sensor harness connector. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to step 14 .
13. Check for poor connections at PCM harness connector. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to step 15 .
14. Replace A/C pressure sensor. After replacing sensor, go to step 16 .
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, clear DTCs. Operate vehicle within conditions for setting this DTC. Recheck DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Check for faulty connections or damaged harness. Observe A/C PRESSURE display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. If DTC P1635 is also set, diagnose DTC P1635 before proceeding. If DTC is not set, go to next step.
3. Start and run engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG. 2 DATA LIST. If voltage reading is 10-16 volts, go to next step. If voltage reading is not 10-16 volts, go to step 5 .
4. Read and record FAILURE RECORDS data for DTC P0560. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC while operating vehicle. Continue operating vehicle until DTC P0560 test runs. If scan tool indicates that DTC P0560 failed this ignition, go to next step. If scan tool does not indicate that DTC P0560 failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S11861645322000101600000) .
5. Install DVOM between battery terminals. Monitor DVOM while running engine at greater than 1000 RPM. If voltage reading is 10-18 volts, go to next step. If voltage reading is not 10-18 volts, go to step 7 .
6. Turn headlights on and place A/C switch on high. Monitor DVOM while running engine at greater than 2000 RPM. If voltage reading is 10-18 volts, go to step 8 . If voltage reading is not 10-18 volts, go to next step.
7. Turn ignition off. Disconnect generator harness connector. Turn ignition on. Connect DVOM between generator harness connector control circuit and engine ground. Using scan tool, command GEN L TERM on. If voltage reading is about battery voltage, go to step 12 . If voltage reading is not about battery voltage, go to step 10 .
8. Compare IGNITION 1 voltage display on scan tool with DVOM voltage reading. If both values are close, see «DIAGNOSTIC AIDS»(ref-9296-S11861645322000101600000) . If both values are not close, go to next step.
9. Check PCM ignition feed circuit for poor connection between ignition switch and PCM. Repair as necessary. After repairs, go to step 14 . If no problem is found, go to step 13 .
10. Check generator control circuit for open or short to ground between generator and PCM. Repair as necessary. After repairs, go to step 14 . If no problem is found, go to next step.
11. Check generator control circuit for faulty connection at PCM. Repair as necessary. After repairs, go to step 14 . If no problem is found, go to step 13 .
12. Check generator control circuit for faulty connection at generator. Repair as necessary. After repairs, go to step 14 . If no problem is found, see «DIAGNOSTIC AIDS»(ref-9296-S11861645322000101600000) .
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Clear DTCs. Start and run engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG. 2 DATA LIST. If voltage reading is 10-18 volts, system is okay. If voltage reading is not 10-18 volts, go to step 2 .

Check for faulty connections or damaged harness. Observe IGNITION 1 display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM). EEPROM contains program information and calibrations required for engine, transaxle, and powertrain diagnostics operation. If PCM detects an internal program fault (check sum error), DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, repeat OBD system check.

Only possible repair is replacement and programming of PCM.

PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM). EEPROM contains program information and calibrations required for engine, transaxle, and powertrain diagnostics operation. DTC will set if PCM does not contain correct program(s) required to operate vehicle.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Using special equipment, program PCM with correct software. Using scan tool, retest for DTC P0602. If DTC P0602 resets, go to next step. If DTC does not reset, system is okay.
3. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, repeat OBD system check.

The PCM output "L" terminal to alternator determines when generator will be turned off. It is on under all normal vehicle operating conditions except during low RPM conditions. Generator is turned off during low RPM conditions to remove excess load from engine. The generator warning light will illuminate anytime ignition is on and engine is not running. The warning light will turn off after engine is running and generator is putting out the desired amperage. DTC will set when engine is running, generator warning light is on, and generator "L" terminal voltage is low while PCM is commanding the generator on and condition is present for more than 10 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor generator. If scan tool indicates that generator is on, go to step 4 . If scan tool does not indicate that generator is on, go to next step.
3. Turn ignition on. Disconnect generator harness connector. Connect a DVOM between generator "L" terminal and a known-good ground. Start engine. Using scan tool, command generator on. Monitor voltage reading on DVOM. If voltage reading changes from zero to 5 volts, diagnose charging system. See appropriate STARTING & CHARGING SYSTEMS article. If voltage reading does not change from zero to 5 volts, go to next step.
4. Check generator "L" circuit for open or short to ground. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to next step.
5. Check generator "L" circuit for short to voltage. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to next step.
6. Check for poor connection at PCM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to next step.
7. Replace PCM. program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Using scan tool, review and record scan tool FAIL RECORDS data. Clear DTCs. Operate vehicle within conditions for setting this DTC. Recheck DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Check for faulty connections or damaged harness. Observe on scan tool display while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

Output driver modules (ODMs) are used by PCM to turn on many of the current-driven devices that are needed to control various engine and transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to device which PCM is commanding on. ODMs have the capability of diagnosing each output circuit individually. DTC will set when there is an improper voltage level on output circuit that controls the Malfunction Indicator Light (MIL).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
2. Check MIL fuse. If fuse is open, locate and repair short to ground in MIL ignition supply circuit or a shorted instrument cluster. Repair as necessary and replace fuse. After repairs, go to step 12 . If fuse is okay, go to next step.
3. Turn ignition off. Disconnect PCM harness connector. Connect a fused jumper wire between a known-good ground and MIL control circuit at PCM harness connector. Turn ignition on, with engine off. Check jumper wire fuse. If fuse blows, repair short to voltage in MIL control circuit or a shorted cluster. If fuse did not blow, check MIL operation. If MIL is illuminated, go to next step. If MIL is not illuminated, go to step 5 .
4. Leave ignition on. Remove jumper wire. Observe MIL operation. If MIL is illuminated, go to step 7 . If MIL is not illuminated, go to step 9 .
5. Remove instrument cluster. Check for open in MIL control circuit. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to next step.
6. Check for open in MIL ignition supply circuit. Repair as necessary. After repairs, go to step 12 . If circuit us okay, go to step 8 .
7. Remove instrument cluster. Check for short to ground in MIL control circuit. After repairs, go to step 12 . If circuit is okay, go to step 10 .
8. Check cluster harness connector for faulty connections. Repair as necessary. After repairs, go to step 12 . If connections are okay, go to step 10 .
9. Check PCM harness connector for faulty connections. Repair as necessary. After repairs, go to step 12 . If connections are okay, go to step 11 .
10. Repair or replace instrument cluster. After repairs, go to step 12 .
11. Replace PCM. program replacement PCM using required equipment. After replacing PCM, go to next step.
12. Using scan tool, review and record scan tool FAIL RECORDS data. Clear DTCs. Operate vehicle within conditions for setting this DTC. Recheck DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Check for faulty connections or damaged harness. Observe on scan tool display while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0108 is also set, diagnose DTC P0108 before proceeding. Go to «DTC P0108: MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE»(ref-9296-S30760965162000101600000) . If DTC P0108 is not set, go to next step.
3. Check if DTC P1111, P1115, and/or P1121 is also set. If any of this DTC is set, go to step 6 . If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal at MAP sensor. If problem is found, go to step 9 . If no problem is found, go to next step.
5. Check for faulty ground circuit terminal connection at PCM. If problem is found, go to step 9 . If no problem is found, go to next step.
6. Check MAP sensor signal circuit for intermittent short to voltage. Repair as necessary. After repairs, go to step 9 . If circuit is okay, go to next step.
7. Check MAP sensor 5-volt reference "A" circuit for intermittent short to voltage. Repair as necessary. After repairs, go to step 9 . If circuit is okay, go to next step.
8. Check ground circuit for intermittent open. Repair as necessary. After repairs, go to next step. If circuit is okay, see «DIAGNOSTIC AIDS»(ref-9296-S27709228832000101600000) .
9. Read and record FAILURE RECORDS data for DTC P1106. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe MAP display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0107 is also set, diagnose DTC P0107 before proceeding. Go to «DTC P0107: MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT - LOW VOLTAGE»(ref-9296-S13154941482000101600000) . If DTC P0107 is not set, go to next step.
3. Check if DTC P1122 is also set. If DTC P1122 is set, go to step 7 . If DTC P1122 is not set, go to next step.
4. Check MAP sensor harness connector for poor connections. Repair as necessary. After repairs, go to step 9 . If connections are okay, go to next step.
5. Check MAP sensor 5-volt reference "A" circuit for poor connection at PCM. Repair as necessary. After repairs, go to step 9 . If circuit is okay, go to next step.
6. Check MAP sensor signal circuit for poor connection at PCM. Repair as necessary. After repairs, go to step 9 . If connections are okay, go to next step.
7. Check MAP sensor 5-volt reference "A" circuit for intermittent open or short to ground. Repair as necessary. After repairs, go to step 9 . If circuit is okay, go to next step.
8. Check MAP sensor signal circuit for intermittent open or short to ground. Repair as necessary. After repairs, go to step 9 . If circuit is okay, see «DIAGNOSTIC AIDS»(ref-9296-S23486083782000101600000) .
9. Using scan tool, read and record FAILURE RECORDS DATA, and clear DTCs. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe MAP display on scan tool MAP while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0113 is also set, diagnose DTC P0113 before proceeding. Go to «DTC P0113: INTAKE AIR TEMPERATURE SENSOR CIRCUIT - HIGH VOLTAGE»(ref-9296-S07692643492000101600000) . If DTC P0113 is not set, go to next step.
3. If DTC P1106, P1115, and/or P1121 is also set, go to step 6 . If these DTCs are not set, go to next step.
4. Check for faulty sensor ground circuit terminal at IAT sensor. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to next step.
5. Check for faulty signal circuit connection at IAT sensor. Repair as necessary. After repairs, go to step 10 . If connection is okay, go to next step.
6. Check IAT signal circuit between IAT sensor connector and PCM for intermittent open. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to next step.
7. Check IAT signal circuit between IAT sensor harness connector and PCM for intermittent short to voltage. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to next step.
8. Check for faulty ground circuit terminal connection at PCM. Repair as necessary. After repairs, go to step 10 . If connection is okay, go to next step.
9. Check for intermittent open or faulty splice in sensor ground circuit. Repair as necessary. After repairs, go to next step. If no problem is found, see «DIAGNOSTIC AIDS»(ref-9296-S11479477922000101600000) .
10. Read and record FAILURE RECORDS data for DTC P1111. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe IAT display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location. Check for skewed IAT sensor. See appropriate SENSOR OPERATING RANGE CHARTS article.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0112 is also set, diagnose DTC P0112 before proceeding. Go to «DTC P0112: INTAKE AIR TEMPERATURE SENSOR CIRCUIT - LOW VOLTAGE»(ref-9296-S30424983442000101600000) . If DTC P0112 is not set, go to next step.
3. Check IAT signal circuit between IAT sensor harness connector and PCM for intermittent short to ground. Repair as necessary. After repairs, go to next step. If circuit is okay, see «DIAGNOSTIC AIDS»(ref-9296-S37066237172000101600000) .
4. Read and record FAILURE RECORDS data for DTC P1112. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that that this DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe IAT display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location. Check for skewed IAT sensor. See appropriate SENSOR OPERATING RANGE CHARTS article.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0117 is also set, diagnose DTC P0117 before proceeding. Go to «DTC P0117: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT - LOW VOLTAGE»(ref-9296-S12279171672000101600000) . If DTC P0117 is not set, go to next step.
3. Check ECT signal circuit between ECT sensor harness connector and PCM for intermittent short to ground. Repair as necessary. After repairs, go to next step. If circuit is okay, see «DIAGNOSTIC AIDS»(ref-9296-S06095930082000101600000) .
4. Read and record FAILURE RECORDS data for DTC P1114. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that that this DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe ECT display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location. Check for skewed ECT sensor. See appropriate SENSOR OPERATING RANGE CHARTS article.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0118 is also set, diagnose DTC P0118 before proceeding. Go to «DTC P0118: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT - HIGH VOLTAGE»(ref-9296-S14913195122000101600000) . If DTC P0118 is not set, go to next step.
3. If DTC P1106, P1111, and/or P1121 is also set, go to step 8 . If none of these DTCs are set, go to next step.
4. Check for faulty sensor ground circuit terminal at ECT sensor. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to next step.
5. Check for faulty signal circuit connection at ECT sensor. Repair as necessary. After repairs, go to step 10 . If connection is okay, go to next step.
6. Check ECT signal circuit between ECT sensor harness connector and PCM for intermittent open. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to next step.
7. Check ECT signal circuit between ECT sensor harness connector and PCM for intermittent short to voltage. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to next step.
8. Check for faulty ground circuit terminal connection at PCM. Repair as necessary. After repairs, go to step 10 . If connection is okay, go to next step.
9. Check for intermittent open or faulty splice in sensor ground circuit. Repair as necessary. After repairs, go to next step. If circuit is okay, see «DIAGNOSTIC AIDS»(ref-9296-S40641038692000101600000) .
10. Read and record FAILURE RECORDS data for DTC P1115. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that that this DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe ECT display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location. Check for skewed ECT sensor. See appropriate SENSOR OPERATING RANGE CHARTS article.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0123 is also set, diagnose DTC P0123 before proceeding. Go to «DTC P0123: THROTTLE POSITION SENSOR CIRCUIT - HIGH VOLTAGE»(ref-9296-S10651499292000101600000) . If DTC P0123 is not set, go to next step.
3. If DTC P1106, P1111, and/or P1115 is also set, go to next step. If any of these DTCs are not set, go to step 5 .
4. Check all 5-volt reference "A" circuit and connected components for intermittent short to voltage. Repair as necessary. After repairs, go to step 9 . If circuits are okay, see «DIAGNOSTIC AIDS»(ref-9296-S23682754292000101600000) .
5. Check TP sensor signal circuit for intermittent short to voltage. Repair as necessary. After repairs, go to step 9 . If circuit is okay, go to next step.
6. Check TP sensor ground circuit for intermittent open. Repair as necessary. After repairs, go to step 9 . If circuit is okay, go to next step.
7. Check TP sensor harness connector for faulty connections. Repair as necessary. After repairs, go to step 9 . If connections are okay, go to next step.
8. Check PCM harness connector for poor connections. Repair as necessary. After repairs, go to next step. If connections are okay, see «DIAGNOSTIC AIDS»(ref-9296-S23682754292000101600000) .
9. Read and record FAILURE RECORDS data for DTC P1121. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that that this DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe TP SENSOR display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, select LAST TST FAIL. Record any other failed DTCs. If DTC P0122 is also set, diagnose DTC P0122 before proceeding. Go to «DTC P0122: THROTTLE POSITION SENSOR CIRCUIT - LOW VOLTAGE»(ref-9296-S29054184272000101600000) . If DTC P0122 is not set, go to next step.
3. If DTC P1107 is also set, go to step 6 . If DTC P1107 is not set, go to next step.
4. Check all 5-volt reference "A" circuit and connected components for intermittent short to ground. Repair as necessary. After repairs, go to step 9 . If circuits are okay, go to step 8 .
5. Check TP sensor 5-volt reference circuit for intermittent open. Repair as necessary. After repairs, go to step 9 . If circuit is okay, go to next step.
6. Check TP sensor signal circuit for intermittent short to ground. Repair as necessary. After repairs, go to step 9 . If circuit is okay, go to next step.
7. Check TP sensor harness connector for poor connections. Repair as necessary. After repairs, go to step 9 . If connections are okay, go to next step.
8. Check PCM harness connector for poor connections. Repair as necessary. After repairs, go to next step. If connections are okay, see «DIAGNOSTIC AIDS»(ref-9296-S36032156412000101600000) .
9. Using scan tool, read and record FAILURE RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, select SPECIFIC DTC INFO for this DTC. If scan tool indicates that that this DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe TP SENSOR display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Warm engine to normal operating temperature. Operate engine at greater than 1200 RPM for 2 minutes. Using scan tool, observe HO2S voltage parameter. If voltage is varying outside of 400-500 mV range, go to next step. If voltage is not varying outside of 400-500 mV range, go step 4 .
3. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates this DTC failed this ignition, go to next step. if scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S36613320902000101600000) .
4. Check for exhaust leak, proper HO2S installation and for damaged wiring. Repair as necessary. After repairs, go to step 15 . If no problems were found, go to next step.
5. Turn ignition on. Disconnect HO2S harness connector. Using a jumper wire, jumper HO2S signal circuit to a good ground. Using scan tool, observe HO2S voltage parameter. If voltage reading is greater than 400 mV, go to next step. If voltage reading is not greater than 400 mV, go to step 10 .
6. Remove jumper wire. Using a DVOM, check voltage on HO2S signal circuit. If voltage reading is about 4.5 volts, go to next step. If voltage reading is not about 4.5 volts, go to step 9 .
7. Check voltage on HO2S low circuit. If voltage reading is about 5 volts, go to step 11 . If voltage reading is not about 5 volts, go to next step.
8. Check HO2S low circuit for open or high resistance. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
9. Check HO2S signal circuit for open or high resistance. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
10. Check HO2S low circuit for short to ground. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 14.
11. Check for faulty connections at HO2S connector. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
12. Check for fuel contamination, engine oil or coolant consumption. Check for improper RTV sealant use. Check for excessive engine coolant or oil consumption. Inspect HO2S for contamination. Eliminate source of contamination before replacing oxygen sensor. After repairs, go to step 15 .
13. Check for faulty connections at PCM. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
15. Using scan tool, clear DTCs. Operate vehicle within FAILURE RECORDS conditions. Recheck for DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Check HO2S 1 heater circuits for intermittent faults. If HO2S 1 heater circuits are okay, replace HO2S 1.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Warm engine to normal operating temperature. Operate engine at greater than 1200 RPM for 2 minutes. Using scan tool, observe HO2S voltage parameter. If voltage is varying outside of 400-500 mV range, go to next step. If voltage is not varying outside of 400-500 mV range, go step 4 .
3. Operate vehicle within FAILURE RECORDS conditions. If scan tool indicates this DTC failed this ignition, go to next step. if scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(ref-9296-S22895546912000101600000) .
4. Check for exhaust leak, proper HO2S installation and for damaged wiring. Repair as necessary. After repairs, go to step 15 . If no problems were found, go to next step.
5. Turn ignition on. Disconnect HO2S harness connector. Using a jumper wire, jumper HO2S signal circuit to a good ground. Using scan tool, observe HO2S voltage parameter. If voltage reading is greater than 400 mV, go to next step. If voltage reading is not greater than 400 mV, go to step 10 .
6. Remove jumper wire. Using a DVOM, check voltage on HO2S signal circuit. If voltage reading is about 4.5 volts, go to next step. If voltage reading is not about 4.5 volts, go to step 9 .
7. Check voltage on HO2S low circuit. If voltage reading is about 5 volts, go to step 11 . If voltage reading is not about 5 volts, go to next step.
8. Check HO2S low circuit for open or high resistance. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
9. Check HO2S signal circuit for open or high resistance. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
10. Check HO2S low circuit for short to ground. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 14.
11. Check for faulty connections at HO2S connector. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
12. Check for fuel contamination, engine oil or coolant consumption. Check for improper RTV sealant use. Check for excessive engine coolant or oil consumption. Inspect HO2S for contamination. Eliminate source of contamination before replacing oxygen sensor. After repairs, go to step 15 .
13. Check for faulty connections at PCM. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
15. Using scan tool, clear DTCs. Operate vehicle within FAILURE RECORDS conditions. Recheck for DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Check HO2S 1 heater circuits for intermittent faults. If HO2S 1 heater circuits are okay, replace HO2S 1.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Perform crankshaft position system variation learn procedure.

The crankshaft position system variation compensating values are stored in the PCM's non-volatile memory after a learn procedure has been performed. If actual crankshaft position variation is not within the crankshaft position system variation compensating values stored in the PCM, DTC P0300 may set.

If the crankshaft position system variation learn procedure cannot be performed successfully, check the following conditions and correct as necessary

1. ECT less than 158°F (70°C).
2. Allow engine to warm-up to greater than 158°F (70°C).
3. PCM related DTC(s) set.
4. Scan tool crankshaft position system variation learn function will be disabled of any PCM DTCs other than DTC P1336 are stored.
5. Camshaft position signal problem detected.
6. 3X reference signal problem detected.
7. 24X reference signal problem detected.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM harness connector. Check resistance between IC and reference low circuit. If resistance is less than 500 ohms, go to step 4 . If resistance is not less 500 ohms, go to next step.
3. Disconnect IC module harness connector. Check for open in IC circuit. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to step 5 .
4. Check for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to step 7 .
5. Check for poor terminal connections at IC module. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to next step.
6. Replace IC module. After replacing module, go to step 8 .
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Connect DVOM between IC and reference low circuit. Connect test light between battery voltage and by-pass circuit. If resistance is greater than 5000 ohms, go to step 4 . If resistance is not greater than 5000 ohms, go to next step.
3. Turn ignition off. Disconnect IC module harness connector. Check for open in by-pass circuit. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to step 5 .
4. Check for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to step 7 .
5. Check for poor terminal connections at IC module. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to next step.
6. Replace IC module. After replacing module, go to step 8 .
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that that this DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, clear DTCs. Start engine and allow it to idle for 2 minutes. Read DTCs. If DTC P1361 sets, go to next step. If DTC does not set, see «DIAGNOSTIC AIDS»(ref-9296-S23686590122000101600000) .
3. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Connect a test light between battery voltage and PCM harness connector by-pass circuit. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
4. Turn ignition on. With test light still connected between battery voltage and PCM harness connector by-pass circuit, use a DVOM to check resistance between PCM harness connector IC circuit and reference low circuit. If resistance is greater than 6000 ohms, go to step 12 . If resistance is not greater than 6000 ohms, go to next step.
5. Turn ignition off. Disconnect IC module 14-pin harness connector. Check resistance between IC module 14-pin harness connector IC circuit and engine ground. If resistance is infinite, go to next step. If resistance is not infinite, go to step 10 .
6. Check by-pass circuit for open. Repair as necessary. After repairs, go to step 15 . If circuit is open, go to next step.
7. Check by-pass circuit for faulty connection at IC module. Repair as necessary. After repairs, go to step 15 . If connection is okay, go to step 14 .
8. Turn ignition off. Disconnect IC module 14-pin harness connector. Turn ignition on. If test light illuminates, go to step 11 . If test light does not illuminate, go to step 14 .
9. Turn ignition off. Disconnect IC module harness connectors. Turn ignition on. Check IC circuit for short to voltage. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
10. Locate and repair short to ground in IC circuit. After repairs, go to step 15 .
11. Locate and repair short to ground in by-pass circuit. After repairs, go to step 15 .
12. Check by-pass circuit for faulty connection at PCM. If faulty connection is found, repair as necessary. After repairs, go to step 15 . If connection is okay, go to next step.
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 15 .
14. Replace IC module. After replacing module, go to next step.
15. Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that that this DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Disconnect ICM. Connect a DVOM between ICM harness connector IC circuit and battery voltage. With ignition on, observe DVOM while moving all related harnesses and connectors. A change in voltage display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Check if DTC P1361 is also set. If DTC P1361 is set, diagnose DTC P1361 first. Go to «DTC P1361: IGNITION CONTROL CIRCUIT - LOW VOLTAGE»(ref-9296-S33319972742000101600000) . If DTC P1361 is not set, go to next step.
3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Using a test light connected to ground, probe by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
4. Turn ignition off. Leave PCM disconnected. Disconnect IC module harness connector. Turn ignition on. Using test light connected to ground, probe by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
5. Locate and repair short to voltage in by-pass circuit. After repairs, go to step 14 .
6. Turn ignition off. Disconnect IC module and PCM harness connectors. Using test light connected to battery voltage, probe IC circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
7. Locate and repair short to ground in IC circuit. After repairs are complete, go to step 14 .
8. Leave ignition off, IC module and PCM connectors disconnected. Using test light connected to ground, probe by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
9. Locate and repair short to ground in by-pass circuit. After repairs, go to step 14 .
10. Leave ignition off, IC module and PCM connectors disconnected. Check for short between IC and by-pass circuits. Repair as necessary. After repairs, go to step 14 . If circuit is okay, go to next step.
11. Leave ignition off and PCM connector disconnected. Reconnect IC module connector. Using DVOM, check resistance between IC and reference low circuits while probing by-pass circuit using test light connected to battery voltage. If resistance switches from less than 500 ohms to greater than 5000 ohms, go to step 13 . If resistance does not switch from less than 500 ohms to greater than 5000 ohms, go to next step.
12. Replace IC control module. After replacing module, go to step 14 .
13. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
14. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, repeat step 2 .

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start and run, see appropriate BASIC DIAGNOSTIC PROCEDURES article.
3. Using scan tool, read and record FAILS RECORD DATA. Operate vehicle within conditions noted in FAILED RECORDS DATA. Read SPECIFIC DTC. If scan tool indicates that that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, go to «DIAGNOSTIC AIDS»(ref-9296-S28293521742000101600000) .
4. Install Injector Test Light (J-34730-2A) to any injector harness connector. Turn ignition on. Using a test light connected to ground, repeatedly touch test light lead to 3X reference signal circuit while observing injector test light. If injector test light blinks/flashes, go to step 8 . If injector test light does not flash, go to next step.
5. Turn ignition off. Disconnect PCM connector. Check 3X reference signal circuit for open or short to ground. If problem is found, go to step 11 . If no problem is found, go to next step.
6. Check for faulty 3X reference signal circuit connection at PCM. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
7. Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or IC module. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to step 10 .
8. Check for faulty connections at IC module. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to next step.
9. Replace IC module. After replacing IC module, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Read and record FAILURE RECORDS data for this DTC. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that that this DTC failed this ignition, return to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe a voltmeter connected to 3X reference circuit at PCM harness connector while moving all related harnesses and connectors. A change in voltage indicates fault location.

Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness.

Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK . After performing OBD system check, diagnose ABS/TCS system. See appropriate ANTI-LOCK article in BRAKES.

If this DTC is set, it indicates that the ABS/TCS system has detected a malfunction which will not allow the EBCM to transmit correct rough data to PCM. Diagnose ABS system. See appropriate ANTI-LOCK article in BRAKES.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, attempt to display ABS data. If ABS data can be displayed, diagnose ABS system. See appropriate ANTI-LOCK article in BRAKES. If ABS data cannot be displayed, diagnose Class II serial data circuit. See BODY CONTROL MODULES article in appropriate ACCESSORIES & EQUIPMENT.

Setting of this DTC indicates that a misfire was detected and that the PCM could not determine if fault was a true misfire or due to operating vehicle on a rough surface. A misfire can be a true misfire with or without setting this DTC. Check PCM or Electronic Brake Control Module (EBCM) for poor connections.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, observe actual EGR position. If actual EGR position is zero percent, go to next step. If actual EGR position is not zero percent, go to step 5 .
3. Turn ignition on, engine off. Using scan tool, select EGR VALVE OUTPUT CONTROL function. Increment EGR valve through all positions while comparing desired to actual EGR position. If desired EGR position remains close to actual EGR position at all commanded positions, go to next step. If desired EGR position does not remain close to actual EGR position, go to step 6 .
4. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Monitor SPECIFIC DTC INFO for this DTC until this DTC test runs. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(ref-9296-S20034579912000101600000) .
5. Disconnect EGR harness connector. Observe actual EGR position on scan tool. If actual EGR position is at zero percent, go to next step. If actual EGR position is not at zero percent, go to step 7 .
6. Using test light connected to battery voltage, probe test light to EGR pintle position sensor ground circuit. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 8 .
7. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Check voltage between ground and EGR pintle position signal circuit. If voltage reading is zero volts, go to step 12 . If voltage reading is not zero volts, go to step 11 .
8. Check EGR pintle position sensor ground circuit for an open between EGR and EGR valve. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
9. Check for poor terminal connections at EGR valve. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
10. Replace EGR valve. If EGR showed signs of excessive heat, check for restricted exhaust. Exhaust restriction may be caused by faulty injector, grounded injector circuit or faulty PCM. Repair as necessary. Also, check for contaminated oil. After replacing EGR valve, go to step 15 .
11. Locate and repair short to voltage in EGR pintle position signal circuit. After repairs, go to step 15 .
12. Check EGR position signal circuit for short to 5-volt reference circuit or short to control circuit. Repair as necessary. After repairs, go to step 15 . If circuits are okay, go to step 14 .
13. Check circuits related to EGR valve for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
15. Using scan tool, select CLEAR INFO or CLEAR DTCs function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
16. Using scan tool, select CAPTURED INFO feature. If any undiagnosed DTCs are displayed, go to affected DTC test.

Check for excessive deposits on EGR valve pintle or seat, causing EGR valve to stick. Check for poor connections at EGR and PCM connector. Check for faulty terminal connections or damaged harness.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Check for DTCs. If any other DTC(s) are set, diagnose affected DTC(s). If no other DTC(s) are set, go to next step.
3. Check EVAP system for improperly installed EVAP canister purge valve or damage to EVAP canister purge valve. Repair as necessary. After repairs, go to step 8 . If no problems were found, go to next step.
4. Turn ignition on, with engine off. Using scan tool, command vent valve off to relieve fuel tank pressure. If scan tool indicates fuel tank pressure at zero in. H2O, go to next step. If scan tool does not indicate fuel tank pressure at zero in. H2O, go to «DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE»(ref-9296-S37201718012000101600000) .
5. Install Fuel Tank Cap Adaptor (J- 41415-40) between fuel filler neck and the fuel filler cap. Connect EVAP Pressure/Purge Diagnostic Station (J-41413) to fuel tank cap adaptor. Using scan tool, capture the FAIL RECORDS data for this DTC. Clear DTCs. Using scan tool, seal EVAP system. Using EVAP station, pressurize system to 5 in. H2O by slowly turning the rotary switch to PRESSURE position. If scan tool indicates fuel tank pressure is 5 in. H2O, go to next step. If scan tool does not indicate a fuel tank pressure of 5 in. H2O, go to «DTC P0452: FUEL TANK PRESSURE SENSOR CIRCUIT - LOW VOLTAGE»(ref-9296-S03292711752000101600000) .
6. Connect EVAP diagnostic station vacuum hose to EVAP canister purge valve canister port. Using scan tool, seal EVAP system. Start and operate engine at idle. Increase idle speed to 1200-1500 RPM. If vacuum reading is greater than zero in. H2O, go to next step. If vacuum reading is not greater than zero in. H2O, see «DIAGNOSTIC AIDS»(ref-9296-S33732791622000101600000) .
7. Replace EVAP canister purge valve. After replacing purge valve, go to next step.
8. Reconnect all EVAP hardware previously disconnected. Turn ignition on, with engine off. Using scan tool, seal EVAP system. Using EVAP diagnostic station, pressurize system to 15 in. H2O by slowly turning rotary switch to PRESSURE position. If EVAP pressure decreases to less than 10 in. H2O within 2 minutes, go to step 3 . If EVAP pressure does not decrease to less than 10 in. H2O within 2 minutes, system is okay.

Check for poor connection at PCM, damaged harness, incorrect vacuum line routing, or faulty or damaged evaporative canister.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Using scan tool, check if other DTCs are present. If other DTCs are present, diagnose affected DTCs first. If no other DTCs are present, go to next step.
3. Allow engine and vehicle temperature to stabilize to ambient temperature. Allowing temperature to stabilize overnight will ensure most accurate results. Turn ignition on, engine off. Using scan tool, compare ECT and IAT sensor readings. If both sensors have the same reading, see «DIAGNOSTIC AIDS»(ref-9296-S03833736182000101600000) . If both sensors do not have the same reading, go to next step.
4. Place a thermometer near IAT sensor. Compare thermometer reading to IAT sensor reading on scan tool. If IAT sensor reading is close to actual ambient temperature, go to next step. If IAT sensor reading is not close to actual ambient temperature, go to step 6 .
5. Replace ECT sensor.
6. Replace IAT sensor.

A cooling system problem is the most likely cause for setting this DTC. Check cooling system.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command A/C relay on and off. If relay turns on and off with each command, see «DIAGNOSTIC AIDS»(ref-9296-S03497339182000101600000) . If relay does not turn on and off with each command, go to next step.
3. Turn ignition off. Disconnect A/C relay. Turn ignition on, with engine off. Using a test light connected to ground, probe relay coil feed circuit. If test light illuminates, go to next step. If test light does not illuminates, go to next step. If test light does not illuminate, go to step 10 .
4. Connect test light between relay control and coil feed circuit. Using scan tool, command A/C relay on and off. If test light turns on and off with each command, go to step 8 . If test light does not turn on and off with each command, go to next step.
5. If test light remains illuminated with each command, go to step 7 . If test light does not remain illuminates with each command, go to next step.
6. Check relay control circuit for short to voltage or open circuit. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check relay control circuit for short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for faulty connections at relay. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Inspect for faulty connections at PCM. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair relay feed circuit. After repair, go to step 13 .
11. Replace A/C relay. After replacing relay, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, repeat step 2 .

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Check if DTC P1585 is also set. If DTC P1585 is set, go to «DTC P1585: CRUISE CONTROL INHIBIT OUTPUT CIRCUIT»(ref-9296-S36703811842000101600000) . If DTC P1585 is not set, go to next step.
3. Turn ignition off. Disconnect cruise control module. Turn ignition on. Using a DVOM, check cruise control status circuit at cruise control module harness connector and ground. If voltage reading is greater than 7 volts, go to next step. If voltage reading is not greater than 7 volts, go to step 5 .
4. Turn ignition off. Reconnect cruise control module harness connector. Disconnect PCM harness connector. Turn ignition on. Using a test light connected to battery voltage, probe cruise engaged status circuit at PCM harness connector. If test light illuminates, go to step 6 . If test light does not illuminate, go to step 7 .
5. Turn ignition off. Disconnect PCM harness connector. Using a test light connected to battery voltage, probe cruise engaged status circuit at PCM harness connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to step 7 .
6. Replace cruise control module. After replacing cruise control module, go to step 9 .
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 9 .
8. Locate and repair short to ground in cruise control status circuit. After repairs, go to next step.
9. Using scan tool, clear DTCs. Start engine and observe DTCs. If this DTC resets, repeat step 2 . If this DTC does not reset, system is okay.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe traction control desired torque. If desired torque is at or about 100 percent, go to step 4 . If desired torque is not at or about 100 percent, go to next step.
3. Turn ignition off. Disconnect Electronic Brake and Traction Control Module (EBTCM) connector. Turn ignition on. Using a DVOM, check voltage between engine ground and EBTCM harness connector desired torque PWM circuit. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step 6 .
4. Turn ignition off. Connect ABS/TCS Pinout Box and Adapter (J39700-25) between EBTCM and EBTCM connector. Using DVOM in Hertz (Hz) scale, check frequency between engine ground and desired torque PWM circuit. Turn ignition on. If frequency is 120-135 Hz, go to next step. If frequency is not 120-135 Hz, go to step 7 .
5. Using DVOM in duty cycle scale, check duty cycle between engine ground and desired torque PWM circuit. Turn ignition on, with engine off. If duty cycle is 10-95 percent, go to step 9 . If duty cycle is not 10-95 percent, go to step 7 .
6. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Check desired torque PWM circuit for open, short to ground or short to voltage. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to step 9 .
7. Check for poor connection at EBTCM. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
8. Replace EBTCM. After replacing EBTCM, go to step 11 .
9. Check for poor connection at PCM. Repair as necessary. After repairs, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Clear DTCs. Turn ignition on and observe DESIRED TORQUE PWM scan tool display. If scan tool indicates that about 100, system is okay. If scan tool does not indicate about 100 percent, return to step 2 .

Check for faulty connections or damaged harness. Observe scan tool DESIRED TORQUE display while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a DVOM, check voltage between ground and cruise control module control circuit at PCM harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6 .
3. Connect DVOM between ground and cruise control inhibit control circuit at PCM harness connector. Monitor reading for about 2 minutes. If current reading is .001-.500 amp, go to step 11 . If current reading is not .001-.500 amp, go to next step.
4. Turn ignition off. Disconnect cruise control module harness connector. Ensure PCM harness connector is disconnected. Turn ignition on. Check voltage between ground and cruise inhibit control circuit. If voltage reading is zero volts, go to step 10 . If voltage reading is not zero volts, go to next step.
5. Locate and repair short to voltage in cruise inhibit control circuit. After repairs, go to step 16 .
6. Turn ignition off. Check ignition feed fuse for cruise control module. If fuse is blown, go to next step. If fuse is not blown, go to step 8 .
7. Repair short to ground in ignition feed circuit for cruise control module. Repair as necessary. Replace fuse. After repairs, go to step 16 .
8. Disconnect cruise control module harness connector. Turn ignition on. Check voltage between ground and ignition feed circuit for cruise control module. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13 .
9. Check cruise inhibit control circuit for open or short to ground. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to next step.
10. Check cruise inhibit control circuit for poor connection at PCM and at stepper motor cruise control module. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to step 14 .
11. Turn ignition off. Reconnect PCM harness connector. Disconnect stepper motor cruise control module harness connector. Turn ignition on. Using a test light, connect test light between cruise inhibit control circuit and ignition feed circuit at stepper motor cruise control module harness connector. Using scan tool in OUTPUT TEST function, cycle cruise inhibit output on and off. If test light flashes on and off, see «DIAGNOSTIC AIDS»(ref-9296-S03579051302000101600000) . If test light does not flash on and off, go to next step.
12. Check cruise control inhibit circuit for poor connection at PCM. Repair as necessary. After repairs, go to step 16 . If connection is okay, go to step 15 .
13. Repair open in ignition feed circuit to stepper motor cruise control module. After repairs, go to step 16 .
14. Replace cruise control module. After replacing module, go to step 16 .
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, repeat step 2 .

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Check if DTC P1631 is also set. If DTC P1631 is set, go to «DTC P1631: THEFT DETERRENT START ENABLE SIGNAL NOT CORRECT»(ref-9296-S07148851882000102100000) . If DTC P1631 is not set, go to next step.
3. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
4. Using scan tool, review and record FAIL RECORDS data. Clear DTCs. Attempt to start engine. If engine starts and continues to run, system is okay. If engine does not start, go to step 2 .

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Ensure battery is fully charged. Attempt to start engine. If engine starts, system is okay. If engine does not start, see appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Perform password learn procedure. See appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT. If password is learned, system is okay.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using a DVOM, check voltage between ground and 5-volt reference circuit. If voltage reading is about 5 volts, go to step 5 . If voltage reading is not about 5 volts, go to next step.
3. Using DVOM, observe voltage while disconnecting all components connected to the 5-volt reference circuit one at a time. If voltage changes when one of the components is disconnected, go to step 8 . If voltage does not change when one of the components is disconnected, go to next step.
4. If voltage reading is less than 4.9 volts, go to step 6 . If voltage reading is not less than 4.9 volts, go to step 7 .
5. Reconnect component(s) that were disconnected earlier. Check another 5-volt reference circuit. If voltage reading is about 5 volts, go to step 9 . If voltage reading is not about 5 volts, go to step 8 .
6. Check all 5-volt reference "A" circuits for short to ground. Repair as necessary. After repairs, go to step 10 . If circuits are okay, go to step 9 .
7. Check all 5-volt reference "A" circuit for short to voltage. Repair as necessary. After repairs, go to step 10 . If circuits are okay, go to step 9 .
8. Replace affected component(s). After replacing component(s), go to step 10 .
9. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
10. Using scan tool, select CLEAR INFO or CLEAR DTCs function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until DTC test runs. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Disconnect and inspect PCM connector. Inspect for damaged pins, corrosion and loose wires. An intermittent problem can be caused by a poor connection, rubbed-through wire insulation or broken wire inside insulation. Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using a DVOM, check voltage between ground and 5-volt reference circuit. If voltage reading is about 5 volts, go to step 5 . If voltage reading is not about 5 volts, go to next step.
3. Using DVOM, observe voltage while disconnecting all components connected to the 5-volt reference circuit one at a time. If voltage changes when one of the components is disconnected, go to step 8 . If voltage does not change when one of the components is disconnected, go to next step.
4. If voltage reading is less than 4.9 volts, go to step 6 . If voltage reading is not less than 4.9 volts, go to step 7 .
5. Reconnect component(s) that were disconnected earlier. Check another 5-volt reference circuit. If voltage reading is about 5 volts, go to step 9 . If voltage reading is not about 5 volts, go to step 8 .
6. Check all 5-volt reference "B" circuits for short to ground. Repair as necessary. After repairs, go to step 10 . If circuits are okay, go to step 9 .
7. Check all 5-volt reference "B" circuit for short to voltage. Repair as necessary. After repairs, go to step 10 . If circuits are okay, go to step 9 .
8. Replace affected component(s). After replacing component(s), go to step 10 .
9. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
10. Using scan tool, select CLEAR INFO or CLEAR DTCs function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until DTC test runs. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for faulty connections or damaged harness. Observe A/C PRESSURE display on scan tool while moving harness and connectors related to A/C refrigerant pressure sensor. A change in scan tool display indicates fault location.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC SYSTEM CHECK»(ref-9296-S00397014642000101600000) . After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a DVOM, check voltage between ground and the delivered torque control circuit at PCM harness connector. If voltage reading is about battery voltage, go to next step. If voltage reading is not about battery voltage, go to step 6 .
3. Check current between ground and delivered torque control circuit at PCM harness connector for at least 2 minutes. If current reading is 0.001-0.500 amps, go to next step. If current reading is not 0.001-0.500 amps, go to step 11 .
4. Turn ignition off. Disconnect EBTCM harness connector. Leave PCM disconnected. Turn ignition on. Using DVOM, check voltage between ground and delivered torque control circuit at PCM harness connector. If voltage reading is zero volts, go to step 10 . If voltage reading is not zero volts, go to next step.
5. Repair short to voltage in delivered torque control circuit. After repairs, go to step 16 .
6. Turn ignition off. Check ignition feed fuse for EBTCM. If fuse is open, go to next step. If fuse is okay, go to step 8 .
7. Locate and repair short to ground in ignition feed circuit for EBTCM. After repairs, replace fuse, then go to step 16 .
8. Disconnect EBTCM harness connector. Turn ignition on. Check voltage between ignition feed circuit for EBTCM and ground. If voltage reading is about battery voltage, go to next step. If voltage reading is not about battery voltage, go to step 13 .
9. Check delivered torque control circuit for open or short to ground. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to next step.
10. Check delivered torque control circuit for poor connection at PCM or at EBTCM. Check EBTCM ignition feed circuit for poor connection at EBTCM. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to step 14 .
11. Turn ignition off. Reconnect PCM harness connector. Disconnect EBTCM harness connector. Turn ignition on. Connect a test light between delivered torque control circuit and ignition feed circuit at EBTCM harness connector. Using scan tool in OUTPUTS TEST function, cycle the delivered torque output on and off. If test light flashes on and off, see «DIAGNOSTIC AIDS»(ref-9296-S15973207582000101600000) . If test light does not flash on and off, go to next step.
12. Check delivered torque control circuit for poor connection at PCM. Repair as necessary. After repairs, go to step 16 . If connection is okay, go to step 15 .
13. Repair open in ignition feed circuit to EBTCM. After repairs, go to step 16 .
14. Replace EBTCM. After replacing EBTCM, go to step 16 .
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM , go to next step.
16. Review and record scan tool FAIL RECORDS data. Clear DTCs. Operate vehicle within FAIL RECORDS conditions. Using a scan tool, monitor Specific DTC info this DTC until DTC test runs. If scan tool indicates that this DTC failed this ignition, go to step 2 . If scan tool does not indicate that this DTC failed this ignition, system is okay.

Check for poor terminal connection. Check harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Check wiring harness for damage. If harness inspection does not reveal a problem, observe display on scan tool while moving connectors and wiring harnesses related to sensor. A change in scan tool display may indicate location of fault. PCM and engine grounds for clean and secure connections.