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Engine Control System - Tests W/codes - 5.7L: Diagnosis Pontiac Firebird IV

Testing & Diagnostics ~51218 words

SELF-DIAGNOSTIC SYSTEM

Note. For On-Board Diagnostic System Check see the BASIC TESTING - 5.7L article.

Note. Powertrain Control Module (PCM) may also be referred to as Vehicle Control Module (VCM) in some diagnostic text and illustrations. Terms may be used interchangeably.

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

There are 4 types of DTC category

  1. Type "A" - Emissions related, turns on MIL the first time DTC sets.
  2. Type "B" - Emissions related, turns on MIL if fault is active for 2 consecutive driving cycles.
  3. Type "C" - Non-emissions related, does not turn on MIL, but will turn on SERVICE light.
  4. Type "D" - Non-emissions related, does not turn on MIL or SERVICE light.

DTC INFO MODE

Used to search for a specific type of stored DTC information. There are 7 choices in this mode. Technician may be instructed to test DTC(s) 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.

DTC STATUS

This selection will display any DTC(s) 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. DTC test which run and passed will cause that affected DTC to be removed from scan tool screen.

LAST TEST FAIL

This selection will display only DTCs that have failed the last time the test ran. The last test may have ran during the previous ignition cycle, if a type "A" or "B" DTC is displayed. For type "C" DTCs, the last failure must have occurred during the current ignition cycle to be displayed as LAST TEST FAIL.

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.

TEST RAN AND PASSED

This message indicates the selected diagnostic test has

  1. Passed the last test.
  2. Ran and passed during this ignition cycle.
  3. Ran and passed since DTCs were last cleared.
  4. Test has not failed since DTCs were last cleared.

If this message is displayed, repair is done. If FAILED THIS IGN. message is displayed, repair is incomplete and further diagnosis is required.

DIAGNOSTIC PROCEDURE

Diagnosis of computerized engine control system should be performed in 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 the «BASIC TESTING - 5.7L»(ref-20656) article.
  2. If DTC(s) were displayed, determine whether codes are hard or intermittent trouble codes. Hard codes will cause MIL to illuminate continuously while engine is running. See «HARD OR INTERMITTENT TROUBLE CODE DETERMINATION»(ref-20512-S11223994622001010200000) . For diagnosing hard codes, proceed to appropriate DTC test. For diagnosing intermittent codes, proceed to INTERMITTENTS in the TESTS W/O CODES article.
  3. If no DTCs are present and a driveability problem exists, refer to SYMPTOMS in the TESTS W/O CODES article. Doing so will help identify proper system or component to check in the SYSTEM/COMPONENT TESTS article.
  4. After necessary repairs are made, clear DTCs, verify vehicle will enter "closed loop" operation and ensure DTC does not reset.

READING TROUBLE CODES

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

TROUBLE CODE DEFINITIONS

Code No.Circuit Affected
P0100MAF Sensor Circuit Insufficient Activity
P0101MAF System Performance
P0102MAF Sensor Circuit-Low Frequency
P0103MAF Sensor Circuit-High Frequency
P0106MAP System Performance
P0107MAP Sensor Circuit Low Voltage
P0108MAP Sensor Circuit High Voltage
P0112IAT Sensor Circuit Low Voltage
P0113IAT Sensor Signal Voltage High
P0117ECT Sensor Circuit Low Voltage
P0118ECT Sensor Signal High Voltage
P0121TP Sensor Circuit Insufficient Activity
P0122TP Sensor Circuit Low Voltage
P0123TP Sensor Circuit High Voltage
P0125ECT Excessive Time To Closed Loop
P0131HO2S Circuit Low Voltage-Bank 1, Sensor 1
P0131HO2S Circuit Low Voltage-Bank 1, Sensor 1
P0132HO2S Circuit High Voltage-Bank 1, Sensor 1
P0133HO2S Slow Response-Bank 1, Sensor 1
P0134HO2S Insufficient Activity-Bank 1, Sensor 1
P0135HO2S Heater Circuit-Bank 1, Sensor 1
P0137HO2S Circuit Low Voltage-Bank 1, Sensor 2
P0138HO2S Circuit High Voltage-Bank 1, Sensor 2
P0140HO2S Insufficient Activity-Bank 1, Sensor 2
P0141HO2S Heater Circuit-Bank 1, Sensor 2
P0151HO2S Circuit Low Voltage Bank 2, Sensor 1
P0152HO2S Circuit High Voltage-Bank 2, Sensor 1
P0153HO2S Slow Response-Bank 2, Sensor 1
P0154HO2S Insufficient Activity-Bank 2, Sensor 1
P0155HO2S Heater Circuit-Bank 2, Sensor 1
P0157HO2S Circuit Low Voltage-Bank 2, Sensor 2
P0158HO2S Circuit High Voltage-Bank 2, Sensor 2
P0160HO2S Insufficient Activity-Bank 2, Sensor 2
P0161HO2S Heater Circuit-Bank 2, Sensor 2
P0171Fuel Trim System Lean-Bank 1
P0174Fuel Trim System Lean-Bank 2
P0175Fuel Trim System Rich-Bank 2
P0200Injector Control Circuit
P0300Engine Misfire Detected
P0301Engine Misfire Detected
P0302Engine Misfire Detected
P0303Engine Misfire Detected
P0304Engine Misfire Detected
P0305Engine Misfire Detected
P0306Engine Misfire Detected
P0307Engine Misfire Detected
P0308Engine Misfire Detected
P0323Ignition High/Low Resolution Circuit Intermittent
P0325Knock Sensor Module Circuit
P0332Knock Sensor Circuit
P0335CKP Sensor Circuit
P0336CKP Sensor System Performance
P0372Ignition High Resolution Circuit
P0400EGR System
P0403EGR Solenoid Control Circuit
P0410AIR System
P0412AIR Solenoid Relay Control Circuit
P0420TWC System Low Efficiency-Bank 1
P0430TWC Low Efficiency-Bank 2
P0441EVAP System Incorrect Purge Flow
P0443EVAP Purge Solenoid Valve Control Circuit
P0500VSS Circuit
P0506Idle System Low, IAC Responding
P0507Idle System High, IAC Responding
P0531A/C Pressure Sensor Circuit Performance
P0563System Voltage High
P0601PCM Memory
P0602PCM Not Programmed
P1107MAP Sensor Circuit Intermittently Low Voltage
P1111IAT Sensor Circuit Intermittent High Voltage
P1112IAT Sensor Circuit Intermittent Low Voltage
P1114ECT Sensor Circuit Intermittent Low Voltage
P1115ECT Sensor Circuit Intermittent High Voltage
P1121TP Sensor Intermittently High Voltage
P1122TP Sensor Intermittent Low Voltage
P1133HO2S Insufficient Switching-Bank 1, Sensor 1
P1134HO2S Transition Time Ratio-Bank 1, Sensor 1
P1153HO2S Insufficient Switching-Bank 2, Sensor 1
P1154HO2S Transition Time Ratio-Bank 2, Sensor 1
P1171Fuel System Lean During Acceleration
P1222Injector Control Circuit Intermittent
P1351IC Circuit Voltage High
P1361IC Circuit Voltage Low
P1371Ignition Low Resolution Circuit
P1380EBTCM DTC Detected Rough Road Data Unusable
P1381Misfire Detected, No EBCM/PCM/VCM Serial Data
P1415AIR System-Bank 1
P1416AIR System-Bank 2
P1441EVAP Control System Flow During Non-Purge
P1508IAC System Low RPM
P1509IAC System High RPM
P1532A/C Evaporator Temp. Circuit Low Voltage
P1533A/C Evaporator Temp. Sensor Circuit High Voltage
P1539A/C Clutch Status Circuit Voltage High
P1543A/C System Performance
P1545A/C Clutch Relay Control Circuit
P1546A/C Clutch Status Circuit Voltage Low
P1572ASR/TCS Circuit Low Voltage Too Long
P1626Theft Deterrent System Fuel Enable Circuit
P1641Fan Control (FC) Relay No. 1 Circuit
P1642Fan Control (FC) Relay No. 2 & 3 Circuit
P1643Engine Speed Output Circuit
P1652VSS Output Circuit
P16571-4 Skip Shift Solenoid Control Circuit
P1661MIL Control Circuit
P16641-4 Skip Shift Light Control Circuit
P1667Reverse Inhibit Solenoid Control Circuit

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 (DTC)»(ref-20512-S20515382332001010200000) .
  2. Apply parking brake, and place transmission in Neutral or Park. Block drive wheels, and start engine. MIL should go out. Operate warm engine at specified RPM 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 codes may require a road test to reset hard failure after DTCs were cleared.
  4. If MIL does not illuminate, all stored DTCs were intermittent failures, except as noted above. NOTE: DTCs will be recorded at various operating times. Some codes 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 (DTC)

To clear DTCs from memory, either to determine if malfunction will occur again or after making necessary repairs, disconnect power supply to ECM/PCM/VCM for at least 30 seconds or clear codes using a scan tool.

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. A scan tool plugged into 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 lights and 6 jumper wires 6" long (one wire with female connectors at both ends, one wire with male connectors at both ends and 4 wires with male and female connectors at opposite ends). 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. This is done by performing ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK located in the BASIC TESTING - 5.7L article. If vehicle does not pass OBD system check, information received may be invalid.

Scan tool is a specialized tester which, when plugged into 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 cuts down diagnostic time dramatically by furnishing input data (voltage signals) which can be compared to specification parameters. See SCAN DATA . 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/VCM; 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 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. See SCAN DATA.

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 TROUBLE CODES

Note. Before clearing DTCs, perform On-Board Diagnostic (OBD) System Check. See the BASIC TESTING - 5.7L article. Record FREEZE FRAME and FAILURE RECORDS for reference during testing. Data will be erased when DTCs are cleared. If PCM/VCM is replaced, NEW PCM/VCM must be programmed using special manufacturer's equipment.

Diagnostic Procedures

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and operate engine at idle. Using scan tool, select ENGINE 1 DATA LIST function and monitor MAF GM/S display. If value is less than 3.9 gm/s, go to step 4). If value is 3.9 gm/s or more, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0100. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on, with engine off. Using DVOM, check voltage between MAF signal circuit and battery ground. DVOM should read about 5 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8).
  5. Connect a test light between MAF sensor ignition feed circuit and ground circuit at MAF sensor harness connector. If test light illuminates, go to step 7). If test light does not illuminate, go to next step.
  6. Connect test light between MAF sensor ignition feed circuit and battery ground. If test light illuminates, go to step 9). If test light does not illuminate, go to step 10).
  7. Check for poor connection at MAF sensor harness terminals. Repair or replace faulty terminal(s). After repairs, go to step 13). If connections are okay, go to step 11).
  8. Disconnect PCM. Check MAF signal circuit between PCM and MAF sensor for open, short to ground, short to MAF sensor ground circuit or short to voltage. Repair as necessary. After repairs, go to step 13). If circuits are okay, go to step 12).
  9. Locate and repair open in ground circuit to MAF sensor. After repairs, go to step 13).
  10. Locate and repair open in ignition feed circuit to MAF sensor. After repairs, go to step 13).
  11. Replace MAF 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. Clear DTC(s) using scan tool. Start and warm engine to normal operating temperature. Using scan tool, select DTC, SPECIFIC, then enter DTC P0100. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If test does not run or ran and failed, repeat step 2).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are present, diagnose affected DTC.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Also, check for vacuum or PCV system leaks, incorrect PCV valve, engine oil dipstick not fully seated or engine oil filler cap loose or missing.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: MAP value decreases by about 100 kPa for every 1000 feet of altitude.
  2. Turn ignition on, with engine off. Using scan tool, select MAP from ENGINE 1 DATA LIST function. If MAP value is more than 100 kPa (sea level), go to next step. If not, go to step 19).
  3. Remove MAP sensor from intake manifold, leaving harness connector connected. Install a hand-held vacuum pump to MAP sensor. Observe MAP sensor reading on scan tool while applying vacuum. Each one in. Hg applied should result in 3-4 kPa drop. Value should change smoothly with each increase in vacuum. If MAP value changed smoothly without any erratic reading, go to next step. If reading is erratic, go to step 19).
  4. Apply up to 20 in. Hg to MAP sensor. If MAP sensor reading is 34 kPa or less, go to next step. If not, go to step 19).
  5. Remove vacuum source from MAP sensor. If MAP sensor reading returns to original value, go to next step. If reading does not return to original value, go to step 19).
  6. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function and enter DTC P0101. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  7. Check for blockage in MAF sensor inlet screen, intake manifold leak, vacuum leak at throttle body, leak at EGR valve flange and pipes, or faulty PCV valve. Repair or replace as necessary. After repairs, go to step 21). If no problem is found, go to next step.
  8. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, with engine off. Using DVOM, check voltage between MAF sensor signal circuit and ground. If DVOM reads about 5 volts, go to next step. If not, go to step 10).
  9. Connect test light between MAF sensor ignition feed circuit and ground circuit at sensor harness connector. If test light illuminates, go to step 13). If test light does not illuminate, go to step 12).
  10. If voltage is less than 4.5 volts, go to step 14). If voltage is more than 4.5 volts, go to next step.
  11. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, with engine off. Using a DVOM, check voltage between MAF sensor signal circuit and ground. If voltage is zero volts, go to step 20). If not, go to step 17).
  12. Connect a test light between MAF sensor ignition feed circuit and chassis ground. 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 harness terminal. Repair or replace as necessary. After repairs, go to step 21). If connection is okay, go to step 18).
  14. Check MAF signal circuit between PCM and MAF sensor for open, short to ground or short to MAF ground circuit. Repair open or shorted circuit. After repairs, go to step 21). If circuits are okay, go to step 20).
  15. Locate and repair open in ground circuit to MAF sensor. After repairs, go to step 21).
  16. Locate and repair open in ignition feed circuit to MAF sensor. After repairs, go to step 21).
  17. Locate and repair short to voltage in MAF sensor signal circuit. After repairs, go to step 21).
  18. Replace MAF sensor. After replacing MAF sensor, go to step 21).
  19. Replace MAP sensor. After replacing MAP sensor, go to step 21).
  20. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  21. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select SPECIFIC DTC, then enter DTC P0101. 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).
  22. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Also, check for vacuum or PCV system leaks, incorrect PCV valve, engine oil dipstick not fully seated or engine oil filler cap loose or missing.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and operate engine at idle. Using scan tool, select ENGINE 1 DATA LIST and monitor MAF sensor grams per second (gm/s) display. If MAF sensor value is less than 3.9 gm/s, go to step 4). If MAF sensor value is more than specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0102. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on, with engine off. Using DVOM, check voltage between MAF signal circuit and battery ground. If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step 8).
  5. Connect test light between MAF sensor ignition feed circuit and ground circuit at harness connector. If test light illuminates, go to step 7). If test light does not illuminate, go to next step.
  6. Connect test light between MAF sensor ignition feed circuit and ground. If test light illuminates, go to step 9). If test light does not illuminate, go to step 10).
  7. Check for poor connection at MAF sensor harness terminals. Repair or replace terminal(s). After repairs, go to step 13). If terminals are okay, go to step 11).
  8. Check MAF signal circuit between PCM and MAF sensor for open, short to ground, or short to MAF ground. Repair as necessary. After repairs, go to step 13). If circuits are okay, go to step 12).
  9. Locate and repair open in ground circuit to MAF sensor. After repairs, go to step 13).
  10. Locate and repair open in ignition feed circuit to MAF sensor. After repairs, go to step 13).
  11. Replace MAF sensor. After replacing MAF sensor, go to step 13).
  12. Replace and program replacement PCM using required equipment. After replacing PCM, go to next step.
  13. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0102. Operate vehicle in 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Also, check for vacuum or PCV system leaks, incorrect PCV valve, engine oil dipstick not fully seated or engine oil filler cap loose or missing.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and operate engine at idle. Using scan tool, select ENGINE 1 DATA LIST and monitor MAF sensor grams per second (gm/s) display. If MAF sensor value is more than 300gm/s, go to step 4). If MAF sensor value is less than specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0103. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect MAF sensor harness connector. Start engine. Using scan tool, monitor MAF sensor grams display again. If MAF sensor value is about 1.9 gm/s, go to next step. If MAF sensor value is not as specified, go to step 7).
  5. Check for poor connection at MAF sensor harness connector terminal. Repair or replace as necessary. After repairs, go to step 10). If harness connector terminals are okay, go to next step.
  6. Replace MAF sensor. After replacing MAF sensor, go to step 10).
  7. Check MAF sensor harness for incorrect routing near secondary ignition wires or components, or solenoids, relays or motors. Correct problem as necessary. After repairs, go to step 10). If routing is okay, go to next step.
  8. Check MAF sensor signal circuit terminal connections at PCM. Repair or replace as necessary. After repairs, go to step 10). If connections are okay, go to next step.
  9. Replace PCM. Program replacement PCM using necessary equipment. After replacing PCM, go to next step.
  10. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0103. 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).
  11. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. Also, check for water entering air intake system to MAF sensor. Water rapidly cools hot wire in sensor, causing a false indication of excessive airflow.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. If DTC P0300 is also present, diagnose DTC. If DTC P0300 is not present, go to next step.
  3. Start and idle engine. Using scan tool, select MAP from ENGINE 1 DATA LIST. If MAP sensor reading is varying more than 6.3 kPa, go to next step. If MAP sensor reading is not varying more than specification, go to step 9).
  4. Turn ignition on, with engine off. Wiggle MAP and PCM sensor harness connectors. Check if MAP value is affected by wiggling harness connectors. If MAP value is being affected, go to step 12). If MAP value is not being affected, go to next step. NOTE: MAP value decreases by about 100 kPa for every 1000 feet of altitude.
  5. Using scan tool, select MAP from ENGINE 1 DATA LIST function. If MAP value is 100 kPa (sea level), go to next step. If MAP value is not 100 kPa, go to step 13).
  6. Remove MAP sensor from intake manifold, leaving harness connector connected. Install a hand-held vacuum pump to MAP sensor. Observe MAP sensor reading on scan tool while slowly applying up to 20 in. Hg vacuum. Each one in. Hg applied should result in 3-4 kPa drop. Value should change smoothly with each increase in vacuum. If MAP value changed smoothly without any erratic reading, go to step 13). If reading is erratic, go to next step.
  7. Apply up to 20 in. Hg to MAP sensor. If MAP sensor reads 34 kPa or less, go to next step. If not, go to step 13).
  8. Remove vacuum source from MAP sensor. If MAP sensor reading returns to original value, go to next step. If reading does not return to original value, go to step 13).
  9. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0106. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  10. Check MAF sensor harness for incorrect routing near secondary ignition or components, solenoids, relays, or motors. Repair as necessary. After repairs, go to step 16). If routing is okay, go to next step.
  11. Check for plugged or leaking vacuum supply to MAP sensor. Repair as necessary. After repairs, go to step 13). If vacuum supply to MAP sensor is okay, go to step 14).
  12. Check for poor terminal connections. Check for rubbed-through wire insulation, broken wire inside insulation or misrouted harness. Repair as necessary. After repairs, go to step 16). If circuits are okay, go to next step.
  13. Replace MAP sensor. After replacing MAP sensor, go to step 16).
  14. Check connections to PCM. Repair as necessary. After repairs, go to step 16). If connections are okay, go to next step.
  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 operate engine to normal operating temperature. Select DTC, SPECIFIC then enter DTC P0106. Operate vehicle within conditions that set 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).
  17. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are present, diagnose affected DTCs.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and operate engine at idle. Using scan tool, select ENGINE 1 DATA LIST and monitor MAP voltage. If MAP voltage is less than .24 volts, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0107. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect MAP sensor harness connector. Connect a fused jumper wire between jumper 5-volt reference circuit and MAP signal circuit at MAP sensor harness connector. Observe MAP voltage display on scan tool. MAP sensor voltage should be about 5 volts. If MAP voltage is as specified, go to step 10). If MAP voltage is not as specified, go to next step.
  5. Using a test light, connect test light between battery voltage and MAP sensor signal circuit at MAP sensor harness connector. Observe MAP voltage display on scan tool. MAP voltage should be about 5 volts. If MAP voltage is as specified, go to next step. If MAP voltage is not as specified, go to step 8).
  6. Turn ignition off. Disconnect PCM harness connector. Check for open or short to ground in 5-volt reference circuit. If circuit is open or shorted, repair as necessary. After repairs, go to step 12). If circuits are okay, go to next step.
  7. Check 5-volt reference circuit at PCM for poor connection. Repair as necessary. After repairs, go to step 12). If connection is okay, go to step 11).
  8. Turn ignition off. Disconnect PCM harness connector. Check MAP sensor circuit for open, short to ground or short to sensor ground circuit. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to next step.
  9. Check for poor connection on MAP sensor signal circuit at PCM. Repair or replace as necessary. After repairs, go to step 12). If connection is okay, go to step 11).
  10. Check MAP sensor signal circuit for poor connection at PCM. Repair as necessary. If terminals are okay, replace MAP sensor. 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, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0107. Operate vehicle within conditions that set 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If other DTC(s) are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM's 5-volt reference circuits are internally connected within PCM. If all MAP sensor circuits are okay, check related 5-volt reference circuits. If it is determined that DTC is intermittent, performing DTC P1107 diagnostics may isolate cause of fault.

  1. 1) Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to step 3). NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 1) to step 3). No test procedures have been omitted.
  2. 3) If engine is running rough or unstable, repair idle problem first. See the TESTS W/O CODES article. After repairs, install scan tool. Start engine. Using scan tool, select ENGINE 1 DATA LIST function and monitor MAP sensor voltage. If MAP sensor voltage is more than 4.2 volts, go to step 5). If MAP sensor voltage is not as specified, go to next step.
  3. 4) Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0108. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. 5) Disconnect MAP sensor harness connector. Note MAP sensor voltage displayed on scan tool. If MAP sensor voltage is less than one volt, go to next step. If MAP sensor voltage is not as specified, go to step 7).
  5. 6) Using a test light connected to battery voltage, probe MAP sensor harness ground circuit. If test light illuminates, go to step 8). if test light does not illuminate, go to step 10).
  6. 7) Check MAP sensor signal circuit for short to voltage or to 5-volt reference circuit. Repair as necessary. After repairs, go to step 10). If circuit is okay, go to step 12).
  7. 8) Using DVOM, check voltage between 5-volt reference circuit and ground. voltage should be 5 volts. If voltage is more than 5 volts, go to step 15). If voltage is less than 5 volts, go to next step.
  8. 9) Check for plugged or leaking vacuum supply to MAP sensor. Repair as necessary. After repairs, go to step 14). If vacuum supply is okay, go to step 13).
  9. 10) Check for poor sensor ground terminal connection at PCM. Replace faulty terminal. After repairs, go to step 16). If terminal is okay, go to next step.
  10. 11) Check continuity of MAP sensor ground circuit. If resistance is more than 5 ohms, repair open or poor terminal connection. After repairs, go to step 16). If resistance is less than 5 ohms, go to next step.
  11. 12) Replace PCM. Program replacement PCM using necessary equipment. After replacing PCM, go to step 16).
  12. 13) Replace MAP sensor. After replacing MAP sensor, go to step 16).
  13. 14) Repair vacuum supply to MAP sensor. After repairs, go to step 16).
  14. 15) Repair 5-volt reference circuit for short to battery voltage. After repairs, go to next step.
  15. 16) Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0108. Operate vehicle within conditions that set 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 3).
  16. 17) Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. If other DTC(s) are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM. If all MAP sensor circuits are okay, check related 5-volt reference circuits. If it is determined that DTC is intermittent, performing DTC P1106 diagnostics may isolate cause of fault.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor IAT display. If IAT reading is more than 302°F (150°C), go to step 4). If IAT reading is as not more than specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0112. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect IAT sensor harness connector. Note IAT sensor value displayed on scan tool. IAT sensor value should be -40°F (-40°C). If IAT value is as specified, go to step 6). If IAT value is not as specified, go to next step.
  5. Turn ignition off. Disconnect PCM harness connector and check IAT 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 IAT sensor, go to step 8).
  7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0112. Operate vehicle within conditions that set 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. If other DTCs are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If temperatures are not within 5°F (3°C), see the SYSTEM/COMPONENT TESTS article. If it is determined that DTC is intermittent, performing DTC P1112 diagnostics may isolate cause of fault.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor IAT display. If IAT value is -40°F (-40°C), go to step 4). If IAT value is not as specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0113. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect IAT sensor harness connector. Connect a fused jumper wire across IAT sensor harness connector terminals. Note IAT sensor value displayed on scan tool. If IAT value is 304°F (151°C), go to step 9). If IAT value is not as specified, go to next step.
  5. Disconnect jumper wire. Connect jumper wire between IAT sensor signal circuit and known good ground. Note IAT sensor value displayed on scan tool. If IAT value is 304°F (151°C), go to step 8). If IAT value is not as specified, go to next step.
  6. Turn ignition off. Disconnect PCM harness connector and check IAT signal circuit for open. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step 11).
  7. Repair IAT sensor signal circuit. After repairs, go to step 12).
  8. Turn ignition off. Disconnect PCM harness connector. Check IAT sensor ground circuit for open. Repair as necessary. After repairs, go to step 10). If circuit is okay, go to step 11).
  9. Replace IAT sensor. After replacing IAT sensor, go to step 12).
  10. Repair IAT sensor ground. 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, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0113. Operate vehicle within conditions that set 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If other DTC(s) are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If temperatures are not within 5°F (3°C), see the SYSTEM/COMPONENT TESTS article.

If it is determined that DTC is intermittent, performing DTC P1111 diagnostics may isolate cause of fault.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor ECT display. If ECT value is more than 302°F (150°C), go to step 4). If ECT value is not as specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0117. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect ECT sensor harness connector. Observe ECT display on scan tool. If ECT value is less than -22°F (-30°C), go to step 6). If ECT value is more than specified, go to next step.
  5. Turn ignition off. Disconnect PCM harness connector and check ECT 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 ECT sensor. After replacing ECT sensor, go to step 8).
  7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0117. Operate vehicle within conditions that set 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If other DTC(s) are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If temperatures are not within 5°F (3°C), see the SYSTEM/COMPONENT TESTS article.

If it is determined that DTC is intermittent, performing DTC P1114 diagnostics may isolate cause of fault.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor ECT display. If ECT value is -40°F (-40°C), go to step 4). If ECT value is not as specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0118. If scan tool indicates this test failed this ignition, go to next step. If scan tool does not indicate this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect ECT sensor harness connector. Observe ECT display on scan tool. If ECT value is 304°F (151°C), go to step 9). If ECT value is not as specified, go to next step.
  5. Connect a fused jumper wire between ECT signal circuit and ground. If ECT value is 304°F (151°C), go to step 8). If ECT value is not as specified, go to next step.
  6. Turn ignition off. Disconnect PCM harness connector and check ECT sensor signal circuit for open. Repair as necessary. After repairs, go to step 7). if circuit is okay, go to step 11).
  7. Repair ECT sensor signal circuit. After repairs, got step 12).
  8. Turn ignition off. Disconnect PCM harness connector. Check ECT sensor ground circuit for open. Repair as necessary. After repairs, go to step 10). If circuit is okay, go to step 11).
  9. Replace ECT sensor. After replacing ECT sensor, go to step 12).
  10. Repair ECT sensor ground circuit. 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, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0118. Operate vehicle within conditions that set 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. If other DTCs are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If engine is allowed to sit overnight, ECT and IAT sensor values should be within a few degrees of each other. If temperatures are not within 5°F (3°C), see the SYSTEM/COMPONENT TESTS article.

If it is determined that DTC is intermittent, performing DTC P1115 diagnostics may isolate cause of fault.

  1. Perform Powertrain On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor TP sensor voltage while moving throttle from closed position to wide open position. Scan tool should display TP sensor voltage at less than one volt to more than 4 volts, as throttle position is changed. If voltage is not as specified, go to next step. If voltage is as specified, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0121. If scan tool indicates this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect TP sensor connector. Observe TP sensor display on scan tool. If about zero volts is displayed, go to next step. If not, go to step 7).
  5. Connect a fused jumper wire between TP sensor 5-volt reference circuit and TP sensor signal circuit. If TP sensor is about 5 volts, go to next step. If TP sensor value is not as specified, go to step 8).
  6. Replace TP sensor. After replacing TP sensor, go to step 10).
  7. Check TP signal circuit for short to voltage. Check TP sensor ground circuit for high resistance between PCM and TP sensor. Check TP sensor ground circuit for poor connection. Repair as necessary. After repairs, go to step 10). If circuits are okay, go to step 9).
  8. Check TP sensor signal circuit or 5-volt reference circuit for poor connection. Check signal circuit or 5-volt reference circuit for high resistance between PCM and TP sensor. Replace as necessary. After repairs, go to step 10). If circuits are okay, go to next step.
  9. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  10. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0121. Operate vehicle within conditions that set 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).
  11. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation. If other DTCs are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM. If it is determined DTC is intermittent, performing DTC P1121 diagnostics may isolate cause of fault.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor TP sensor voltage with throttle closed. If TP sensor voltage is less than 0.2 volt, go to step 4). If TP sensor voltage is not as specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0122. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect TP sensor connector. Connect a fused jumper wire between 5-volt reference circuit and TP signal circuit at connector. Observe TP sensor voltage display on scan tool. If TP voltage is more than 4.7 volts, go to next step. If TP sensor voltage is not as specified, go to step 8).
  5. Connect test light between battery voltage and TP sensor signal circuit at connector. Observe TP sensor voltage on scan tool. If TP sensor is more than 4.7 volts, go to next step. If TP sensor is not as specified, go to step 8).
  6. Turn ignition off. Disconnect PCM and check 5-volt reference circuit for short or open circuit. Repair circuit as necessary. After repairs, go to step 12). If circuit is okay, go to next step.
  7. Check 5-volt reference circuit for poor connection at PCM. Repair or replace terminals as necessary. After repairs are complete, go to step 12). If terminals are okay, go to step 11).
  8. Turn ignition off. Disconnect PCM and check TP signal circuit for an open, short to ground, or short to sensor ground circuit. Repair as necessary. After repairs, go to step 12). If circuit is okay, go to next step.
  9. Check TP sensor signal circuit for poor connection at PCM terminal. Repair or replace terminals as necessary. After repairs, go to step 12). If terminals are okay, go to step 11).
  10. Replace TP sensor. After replacing TP sensor, go to step 12).
  11. Replace PCM. Program replacement PCM using required equipment. Go to next step.
  12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0122. Operate vehicle within conditions that set 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If other DTC(s) are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring. The PCM 5-volt reference circuits are internally connected within PCM. If it is determined that DTC is intermittent, performing DTC P1122 diagnostics may isolate cause of fault.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor TP sensor voltage with throttle closed. If TP sensor voltage is more than 4.7 volts, go to step 4). If TP sensor voltage is 4.7 volts or less, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0123. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect TP sensor connector. Observe TP sensor voltage display on scan tool. If TP sensor voltage is less than 0.2 volt, go to next step. If TP sensor voltage is more than specified, go to step 8).
  5. Connect test light between battery voltage and TP sensor ground circuit at connector. If test light illuminates, go to next step. If test light does not illuminate, got step 9).
  6. Using DVOM, check voltage between ground and 5-volt reference circuit. voltage should be 5 volts. If voltage is more than specified, go to step 12). If voltage is less than specified, go to next step.
  7. Replace TP sensor. After replacing TP sensor, go to step 13).
  8. Turn ignition off. Disconnect PCM connector. Turn ignition on, with engine off. Check TP signal circuit for short to voltage or short between TP sensor signal circuit and EBTCM. Repair as necessary. After repairs, go to step 13). If circuit is okay, go to step 11).
  9. Turn ignition off. Disconnect PCM connector. Check TP sensor ground circuit connection at PCM. Repair or replace terminal as necessary. After repairs, go to step 13). If terminal is okay, go to next step.
  10. Check for open in TP sensor ground circuit. Repair as necessary. After repairs, go to step 13). If circuit is okay, go to next step.
  11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 13).
  12. Repair 5-volt reference circuit for short to voltage. After repairs, 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 DTC P0123. Operate vehicle within conditions that set 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

If other DTC(s) are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring. PCM 5-volt reference circuits are internally connected within PCM.

If it is determined that DTC is intermittent, performing DTC P1121 diagnostics may isolate cause of fault.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. If other ECT related Diagnostic Trouble Codes (DTCs) are present, diagnose affected DTC(s). If no other related DTC(s) are present, go to next step.
  3. Turn ignition on, with engine off. Disconnect ECT sensor connector. If scan tool reads less than -31°F (-35°C), go to step 4). If scan tool reads -31°F (-35°C) or more, go to «DTC P0117»(ref-20512-S04202009862001010200000) , ECT SENSOR CIRCUIT VOLTAGE LOW test.
  4. Connect a fused jumper wire across ECT sensor harness terminals. If scan tool indicates more than 302°F (150°C), go to next step. If scan tool indicates specified value or less, go to «DTC P0118»(ref-20512-S34713933462001010200000) , ECT SENSOR CIRCUIT VOLTAGE HIGH test.
  5. Reconnect ECT sensor. Start and warm engine to normal operating temperature. Using scan tool, select ENGINE 1 DATA LIST and observe ECT sensor, with engine at idle. If coolant temperature reading is at least 140°F (60°C), recheck system on a cold start. See DIAGNOSTIC AIDS. If coolant temperature is not as specified, go to next step.
  6. Using DVOM, check ECT sensor resistance. See the «ECT TEMPERATURE-TO-RESISTANCE VALUES»(ref-20512-S03965763532001010200000) table. If ECT resistance value is close as indicated, go to next step. If ECT resistance value is not as specified, go to step 8). ECT TEMPERATURE-TO-RESISTANCE VALUES Temperature °F (°C) Ohms 212 (100) 177 194 (90) 241 158 (70) 467 122 (50) 973 104 (40) 1459 86 (30) 2238 68 (20) 3520 50 (10) 5670
  7. For cooling system problem, check thermostat operation, coolant level, coolant-to-water ratio, cooling fan operation, etc. After repairs, go to step 9).
  8. Replace ECT sensor. After replacing ECT sensor, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0125. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data may aid in locating intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS can be useful in determining how many miles since DTC set. It can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.) that are noted. This will isolate when DTC failed. If other DTC(s) are set that share same ground and/or 5-volt reference circuit, check for faulty connections or wiring.

If engine is allowed to sit overnight, ECT and IAT values should display within a degrees of each other. If temperature is not within 5°F (3°C), check for faulty ECT or IAT sensor.

If it is determined that DTC is intermittent, performing DTC P1114 or P1115 diagnostic may isolate cause of fault.

If ECT is more than 140°F (60°C), this indicates that engine is capable of reaching proper temperature, but not necessarily in correct amount of time. This test must be repeated on a cold engine, engine coolant and intake air temperature at less than 122°F (50°C) and within 5°F (3°C) of each other. When starting a cold engine, engine should reach specified temperature within 7 minutes. If specified temperature is not reached within specified time, check coolant level, thermostat operation or if cooling fans are operating at all times.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage, with engine at idle. If HO2S voltage is less than 200 mV, go to step 4). If HO2S voltage is more than specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0131. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect HO2S connector. Connect a fused jumper wire between PCM connector (harness side), HO2S low circuit and ground. If sensor voltage is 375-525 mV, see DIAGNOSTIC AIDS. If sensor voltage is not within specified value, go to next step.
  5. Turn ignition off. Disconnect PCM connector. Check HO2S signal circuit for short to ground or short to sensor ground circuit. Repair circuit as necessary. After repairs, go to next step. If circuit(s) are okay, go to step 7).
  6. Repair HO2S signal circuit. After repairs, go to step 8).
  7. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0131. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Check for HO2S pigtail wire for breaks, contamination or grounding on exhaust manifold. Check for intermittent ground in signal wire between sensor connector and sensor.

Check for lean injector(s). Perform Injector Balance Test. See the SYSTEM/COMPONENT TESTS article. Check for fuel contamination, improper fuel pressure or exhaust leak, especially near HO2S. Check for vacuum or crankcase leak, causing a lean condition.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage, with engine speed at about 1200 RPM. If HO2S voltage is more than 774 mV, go to step 4). If HO2S reading is less than specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, SPECIFIC, and then P0132. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. While monitoring HO2S voltage, remove HO2S heater fuse. If HO2S voltage drops to within a range of 375-525 mV with power disconnected, go to next step. If voltage does not drop to within specified range, go to step 7).
  5. Disconnect HO2S connector. Connect a fused jumper wire between ground and HO2S connector (PCM side), low signal circuit. If reading is 375-525 mV, see DIAGNOSTIC AIDS. If reading is not as specified, go to next step.
  6. While monitoring HO2S voltage, remove HO2S heater fuse. If HO2S voltage drops to within a range of 375-525 mV with power disconnected, go to step 9). If voltage does not drop to within specified range, go to step 8).
  7. Turn ignition off. Disconnect PCM connector for HO2S signal circuit wire. Disconnect HO2S connector. Turn ignition on. Using DVOM, check voltage between ground and sensor signal circuit at PCM connector. If voltage is present, go to next step. If voltage is not present, see DIAGNOSTIC AIDS.
  8. Repair short to voltage in HO2S signal circuit. After necessary repairs, go to step 12).
  9. Repair shorted HO2S signal circuit and HO2S heater battery positive circuit. After repairs, go to next step. If circuits are okay, go to step 11).
  10. Replace HO2S. After replacing HO2S, go to step 12).
  11. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0132. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the SYSTEM/COMPONENT TESTS article.

Check EVAP system for fuel saturation. Check MAF sensor. Disconnect MAF connector and see if rich condition is corrected. If rich condition is corrected, check for incorrectly installed MAF sensor or faulty MAF sensor. Check HO2S wires for breaks or contamination. Check TP sensor. See the SYSTEM/COMPONENT TESTS article.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If other DTC(s) are present, diagnose affected DTC(s) first.
  2. Start and warm engine to normal operating temperature. Using scan tool, select ENGINE 1 DATA LIST and operate vehicle within parameters when DTC was set. Using scan tool, select DTC INFO and monitor FAIL THIS IGN data. If scan tool indicates that DTC P0133 test failed, go to next step. If scan tool does not indicate that DTC P0133 test failed, see DIAGNOSTIC AIDS.
  3. If scan tool also indicates that «DTC P0153»(ref-20512-S27453569172001010200000) test failed, go to step 8). If scan tool does not indicate that P0153 test failed, go to next step.
  4. Check exhaust system for leaks. Repair as necessary. After repairs, repeat step 2). If exhaust is okay, go to next step.
  5. Ensure Bank 1 HO2S 1 is securely installed. Check terminals for corrosion or damaged wiring. Repair as necessary. After repairs, go to step 9). If wiring and terminals are okay, go to next step.
  6. Disconnect Bank 1 HO2S 1. Connect a fused Jumper wire between ground and PCM connector (PCM side), HO2S low signal circuit. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage is 375-525 mV, go to next step. If HO2S voltage is not as specified, go to step 10).
  7. Connect a fused jumper wire between ground and PCM connector (PCM side), Bank 1 HO2S 1 high and low signal circuit. Using scan tool, monitor voltage. If voltage is less than 200 mV, go to step 12). If voltage is more than 200 mV, go to step 11).
  8. Replace HO2S. Determine cause of sensor contamination, otherwise new sensor will be damaged. After replacing HO2S, go to step 13).
  9. Repair or replace wiring or terminal as necessary. After repairs, go to step 13).
  10. Repair open in sensor low signal circuit or grounded high signal circuit. After repairs, go to step 13).
  11. Repair open in sensor high signal circuit or faulty PCM connectors. After repairs, go to step 13).
  12. Replace Bank 1 HO2S 1 sensor. After replacing HO2S, go to next step.
  13. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0133. 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

A malfunction in HO2S heater circuit will set DTC. Check circuit for intermittent open or faulty connectors. Oxygen supply inside HO2S is provided through wires.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Increase engine speed to more than 1200 RPM for 2 minutes. Using scan tool, select ENGINE 1 DATA LIST and monitor Bank 1 HO2S 1 voltage. If voltage is varying outside range of 352-552 mV, go to next step. If voltage is not varying as specified, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0134. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition on, with engine off. Disconnect Bank 1 HO2S 1 connector. Connect a fused jumper wire between ground and PCM connector (PCM side), high and low signal circuits. If voltage is less than 200 mV, go to step 8). If voltage is more than 200 mV, go to next step.
  5. Remove jumper wire. Using DVOM, check voltage between sensor high and heater ground circuit, on PCM harness side. If voltage is more than 375 mV, go to next step. If voltage is not as specified, go to step 7).
  6. Turn ignition off. Disconnect PCM connector. Check resistance of Bank 1 HO2S 1 low circuit. If resistance is more than 2 ohms, go to step 13). If resistance is 2 ohms or less, go to step 9).
  7. Turn ignition off. Disconnect PCM connector. Check resistance of Bank 1 HO2S 1 signal circuit. If resistance is more than 2 ohms, go to step 13). If resistance is 2 ohms or less, go to step 10).
  8. Check for poor low circuit signal terminal connection at Bank 1 HO2S 1 connector. Repair or replace terminal as necessary. After repairs, go to step 13). If terminals are okay, go to step 11).
  9. Check for poor low signal terminal connection at PCM harness. Repair or replace terminals as necessary. After repairs, go to step 13). If terminals are okay, go to step 12).
  10. Check for poor signal circuit terminal connection at PCM harness. Repair or replace terminals as necessary. After repairs, go to step 13). If terminals are okay, go to step 12).
  11. Replace Bank 1 HO2S 1 sensor. After replacing HO2S, go to step 13).
  12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
  13. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0134. 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Oxygen supply inside HO2S is necessary for its proper operation. This supply of oxygen is provided through HO2S wires. Inspect all wires and terminals for breaks or contamination.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If engine has been operating, allow engine to cool for about one hour before proceeding with tests.
  2. Turn ignition off. Turn ignition, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage goes from bias voltage to more than 700 mV or less than 300 mV, see DIAGNOSTIC AIDS. If HO2S voltage does not respond as indicated, go to next step.
  3. Check HO2S ignition feed fuse. If fuse is faulty, go to step 11). If fuse is okay, go to next step.
  4. Raise and support vehicle. Disconnect HO2S connector. Connect test light to chassis ground and probe ignition feed circuit at HO2S connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
  5. Connect test light between ignition feed and heater ground at HO2S connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  6. Using DVOM, check resistance between ignition feed and heater ground at HO2S connector. If resistance is 3.5-14.0 ohms, go to step 9). If resistance is not as specified, go to step 10).
  7. Repair open in HO2S ignition feed circuit. After repairs, go to step 12).
  8. Repair open in HO2S heater ground circuit. After repairs, go to step 12).
  9. Check for poor terminal connection at HO2S connector. Repair or replace terminals. After repairs, go to step 12).
  10. Replace HO2S. After replacing HO2S, go to step 12).
  11. Locate and repair short to ground in HO2S ignition feed circuit and replace fuse. After repairs, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0135. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data may aid in locating intermittent condition. If DTC cannot be duplicated, information included in this data can be useful in determining how many miles since DTC has set.

The FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.) that are noted. This will isolate when DTC failed.

The heater diagnostic will only run on a cold start and only once per ignition cycle. Oxygen supply inside HO2S is necessary for proper operation and is provided through HO2S wires. Check all HO2S wires and connections for breaks or contamination.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Operate vehicle under following parameters, engine coolant temperature at more than 118°F (48°C), system in closed loop, fuel trim enabled, air/fuel ratio of 14.6:1-14.8:1, TP sensor angle of 3-20 percent, and HO2S signal at less than 39 mV for 30 seconds. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. Voltage should be . If voltage is less than 39 mV, go to step 4). If voltage is not as specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0137. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect HO2S connector. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S low circuit ground. If voltage is 375-525 mV, see DIAGNOSTIC AIDS. If voltage is not as specified, go to next step.
  5. Turn ignition off. Disconnect PCM connector. Check HO2S circuit for short to ground or short to sensor ground circuit. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step 7).
  6. Repair HO2S 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, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Then, select DTC, SPECIFIC and then enter DTC P0137. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If test does not run or failed, repeat step 2).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If other undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

Check HO2S wires grounding against exhaust manifold. Oxygen supply inside HO2S is necessary for its proper operation. This supply of oxygen is provided through HO2S wires. Inspect all wires and terminals for breaks or contamination.

Check for lean fuel injector(s) or low fuel pressure. Perform injector balance test. See the SYSTEM/COMPONENT TESTS article. Check for fuel contamination. Water can cause a lean condition and can set a DTC. Check for exhaust leaks near HO2S, vacuum or crankcase leaks that can cause a lean condition. Check for faulty HO2S.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Increase engine speed to about 1200 RPM. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S display. If voltage is more than 930 mV, go to step 4). If voltage is 930 mV or less, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0138. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. While monitoring HO2S voltage, remove HO2S heater fuse. If HO2S voltage drops to within a range of 375-525 mV with power disconnected, go to next step. If voltage does not drop to within specified range, go to step 7).
  5. Disconnect HO2S harness connector. Connect a fuse jumper wire between ground and PCM connector (PCM side), HO2S low signal (PCM side) circuit. If reading is 375-525 mV, see DIAGNOSTIC AIDS. If reading is not as specified, go to next step.
  6. While monitoring HO2S voltage, remove HO2S heater fuse. If HO2S voltage drops to within a range of 375-525 mV with power disconnected, go to step 9). If voltage does not drop to within specified range, go to step 8).
  7. Turn ignition off. Disconnect PCM connector for HO2S signal circuit wire. Disconnect HO2S harness connector. Turn ignition on. Using DVOM, check voltage between ground and sensor signal circuit at PCM connector. If voltage is present, go to next step. If voltage is not present, see DIAGNOSTIC AIDS.
  8. Repair short to voltage in HO2S signal circuit. After necessary repairs, go to step 12).
  9. Repair shorted HO2S signal circuit and HO2S heater battery positive circuit. After repairs, go to next step. If circuits are okay, go to step 11).
  10. Replace HO2S. After replacing HO2S, go to step 12).
  11. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0138. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Check HO2S wires grounding against exhaust manifold. Oxygen supply inside HO2S is necessary for its proper operation. This supply of oxygen is provided through HO2S wires. Inspect all wires and terminals for breaks or contamination.

Check for rich fuel injector(s) or fuel pressure being too high. Perform injector balance test. See SYSTEM/COMPONENT TESTS article. Check for saturated EVAP canister or incorrectly installed MAF sensor. Disconnect MAF sensor and observe if rich condition is corrected. Check for leaking fuel pressure regulator or leaking regulator vacuum hose. Check TP sensor. An intermittent TP sensor output will cause system to go rich.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Increase engine speed to more than 1200 RPM for 2 minutes. Using scan tool, select ENGINE 1 DATA LIST and monitor bank 1 HO2S 1 voltage. If voltage is varying outside of 391-491 mV range, go to next step. If not, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0140. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition on, with engine off. Disconnect Bank 1 HO2S 1 harness connector. Connect a fused jumper wire between ground and PCM connector (PCM side) high and low signal circuits. If voltage is less than 200 mV, go to step 8). If voltage is more than 200 mV, go to next step.
  5. Remove jumper wire. Using DVOM, check voltage between HO2S sensor high signal circuit and ground circuit. If voltage is more than 375 mV, go to next step. If voltage is less than 375 mV, go to step 7).
  6. Turn ignition off. Disconnect PCM harness connector. Check resistance of Bank 1 HO2S 1 low circuit. If resistance is more than 2 ohms, repair open or poor connection as necessary. After repairs, go to step 13). If circuit is okay, go to step 9).
  7. Turn ignition off. Disconnect PCM harness connector. Check resistance of Bank 1 HO2S 1 signal circuit. Resistance should be 2ohms. If resistance is more than 2 ohms, repair open or poor connection as necessary. After repairs, go to step 13). If circuit is okay, go to step 10).
  8. Check for poor Bank 1 HO2S 1 signal or low circuit terminal connection at HO2S harness connector. Repair or replace terminals as necessary. After repairs, go to step 13). If terminals are okay, go to step 11).
  9. Check for poor Bank 1 HO2S 1 low circuit terminal connection at PCM and replace terminals if necessary. After repairs or replacing terminals, go to step 13). If terminals are okay, go to step 12).
  10. Check for poor Bank 1 HO2S 1 signal circuit terminal connection at PCM and replace terminals if necessary. After repairs or replacing terminals, go to step 13). If terminals are okay, go to step 12).
  11. Replace Bank 1 HO2S 1. After replacing HO2S, go to step 13).
  12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
  13. Clear DTC(s) using scan tool. Start and warm engine to normal operating temperature. Using scan tool, select DTC, SPECIFIC, then enter DTC P0140. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If test does not run or failed, repeat step 2).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If other DTC(s) are displayed that have not been diagnosed, go to appropriate DTC.

Oxygen supply inside HO2S is necessary for its proper operation. This supply of oxygen is provided through HO2S wires. Inspect all wires and terminals for breaks or contamination.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. If engine has been operating, allow engine to cool down for at least one hour before proceeding with test. Turn engine off. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S goes from bias voltage to less than 300 mV or more than 700 mV, see DIAGNOSTIC AIDS. If HO2S does not go to bias voltage or less than 300 mV or more than 700 mV, go to next step.
  3. Check HO2S ignition feed fuse. If fuse is faulty, go to step 11). If fuse is okay, go to next step.
  4. Raise and support vehicle. Disconnect HO2S harness connector. Connect a test light to chassis ground. Probe ignition feed circuit at HO2S harness connector at PCM side. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
  5. Connect test light to HO2S ignition feed and HO2S heater ground circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  6. Using DVOM, check resistance between HO2S ignition feed and heater ground at HO2S harness connector. Resistance should be 3.5-14.0 ohms. If resistance is as specified, go to step 9). If resistance is not as specified, go to step 10).
  7. Repair open in HO2S ignition feed circuit to HO2S. After repairs, go to step 12).
  8. Repair open in HO2S heater ground circuit. After repairs, go to step 12).
  9. Check for poor HO2S harness terminals and replace as necessary. After replacing terminals, go to step 12). If HO2S harness terminals are okay, go to next step.
  10. Replace HO2S. After replacing sensor, go to step 12).
  11. Locate and repair short to ground in HO2S feed circuit and replace fuse. After repairs, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0141. Operate vehicle within conditions that set 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

Using FREEZE FRAME and/or FAILURE RECORDS data may aid in locating intermittent condition. If DTC cannot be duplicated, information included in this data can be useful in determining how many miles since DTC has set.

The FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.) that are noted. This will isolate when DTC failed.

The heater diagnostic will only run on a cold start and only once per ignition cycle. Oxygen supply inside HO2S is necessary for proper operation and is provided through HO2S wires. Check all HO2S wires and connections for breaks or contamination.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage, with engine at idle. If HO2S voltage is less than 200 mV, go to step 4). If HO2S voltage is more than specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0151. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect HO2S harness connector. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S low circuit. If sensor voltage is within specified value of 375-525 mV, see DIAGNOSTIC AIDS. If sensor voltage is not within specified value, go to next step.
  5. Turn ignition off. Disconnect PCM harness connector. Check HO2S signal circuit for short to ground or short to sensor ground circuit. Repair circuit as necessary. After repairs, go to next step. If circuit(s) are okay, go to step 7).
  6. Repair HO2S signal circuit. After repairs, go to step 8).
  7. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0151. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Check for oxygen sensor pigtail wire for breaks, contamination or grounding on exhaust manifold. Check for intermittent ground in signal wire between sensor connector and sensor.

Check for lean injector(s). Perform Injector Balance Test. See the SYSTEM/COMPONENT TESTS article. Check for fuel contamination, improper fuel pressure or exhaust leak, especially near oxygen sensor. Check for vacuum or crankcase leak, causing a lean condition.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage, with engine about 1200 RPM. If HO2S voltage is more than 774 mV, go to step 4). If HO2S reading is less than specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0152. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Remove HO2S heater fuse, while monitoring HO2S voltage. If voltage is within range of 375-525 mV, go to next step. If voltage is not within range 375-525 mV, go to step 7).
  5. Reinstall fuse. Disconnect HO2S harness connector. Connect a fused jumper wire between ground and PCM connector (PCM side) HO2S low signal circuit. If voltage is within range of 375-525 mV, go to step 10). If voltage is not within range of 375-525 mV, go to next step.
  6. Remove HO2S heater fuse. Observe HO2S voltage. If voltage is within range of 375-525 mV, go to step 9). If voltage is not within range of 375-525 mV, go to step 8).
  7. Turn ignition off. Disconnect HO2S signal circuit connector from PCM. Disconnect HO2S harness connector. Turn ignition on. Using DVOM, check voltage on sensor signal circuit at PCM harness connector. If any voltage is present, go to next step. If voltage is not present, see DIAGNOSTIC AIDS.
  8. Repair short to voltage in HO2S signal circuit. After repairs, go to step 12).
  9. Repair shorted HO2S signal circuit and HO2S heater battery positive circuit. After repairs, go to next step. If circuits are okay, go to step 11).
  10. Replace HO2S. After replacing HO2S, go to step 12).
  11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0152. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the SYSTEM/COMPONENT TESTS article.

Check EVAP system for fuel saturation. Check MAF sensor. Disconnect MAF harness connector and see if rich condition is corrected. If rich condition is corrected, check for incorrectly installed MAF sensor or faulty MAF sensor. Check HO2S wires for breaks or contamination. Check TP sensor. See the SYSTEM/COMPONENT TESTS article.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. Go to next step. NOTE: If other DTC(s) are present, diagnose affected DTC(s) first.
  2. Start and warm engine to normal operating temperature. Using scan tool, select ENGINE 1 DATA LIST and operate vehicle within parameters when DTC was set. Using scan tool, select DTC INFO and monitor FAIL THIS IGN data. If scan tool indicates that DTC P0153 test failed, go to next step. If scan tool does not indicate that this test failed, see DIAGNOSTIC AIDS.
  3. If scan tool also indicate that DTC P0133 test failed, go to step 8). If scan tool does not indicate that DTC P0133 test failed, go to next step.
  4. Check exhaust system for leaks. Repair as necessary. After repairs, repeat step 2). If exhaust is okay, go to next step.
  5. Ensure Bank 2 HO2S 1 is securely installed. Check corroded terminals or damaged wiring. Repair as necessary. After repairs, go to step 9). If wiring and terminals are okay, go to next step.
  6. Disconnect Bank 2 HO2S 1. Connect a fused jumper wire between ground and PCM connector (PCM side), low signal ground circuit. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage is 375-525 mV, go to next step. If HO2S voltage is not as specified, go to step 10).
  7. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S 1 high and low signal circuits. Using scan tool, monitor voltage. If voltage is less than 200 mV, go to step 12). If voltage is more than 200 mV, go to step 11).
  8. Replace oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After replacing oxygen sensor, go to step 13).
  9. Repair or replace wiring or terminal as necessary. After repairs, go to step 13).
  10. Repair open in sensor ground circuit or grounded sensor signal circuit. After repairs, go to step 13).
  11. Repair open in sensor signal circuit or faulty PCM connectors. After repairs, go to step 13).
  12. Replace Bank 2 HO2S 1 sensor. After replacing oxygen sensor, go to next step.
  13. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0153. 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

A malfunction in HO2S heater circuit will set DTC. Check circuit for intermittent open or faulty connectors. Oxygen supply inside HO2S is provided through HO2S wires.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. Go to next step.
  2. Start and warm engine to normal operating temperature. Increase engine speed to more than 1200 RPM for 2 minutes. Using scan tool, select ENGINE 1 DATA LIST and monitor Bank 2 HO2S 1 voltage. If voltage is varying outside a range of 352-552 mV, go to next step. If voltage is not varying outside a of specified range, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0154. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition on, with engine off. Disconnect Bank 2 HO2S 1 harness connector. connect a fuse jumper wire between ground and PCM connector ((PCM side), HO2S high and low signal circuits. If voltage is less than 200 mV, go to step 8). If voltage is more than 200 mV, go to next step.
  5. Remove jumper wire. Using DVOM, check voltage between sensor high and heater ground circuit on PCM harness side. If voltage is more than 375 mV, go to next step. If voltage is as specified, go to step 7).
  6. Turn ignition off. Disconnect PCM harness connector. Check continuity of Bank 2 HO2S 1 low circuit. Repair as necessary. After repairs, go to step 13). If circuit is okay, go to step 9).
  7. Turn ignition off. Disconnect PCM harness connector. Check resistance of Bank 2 HO2S 1 signal circuit. If resistance is more than 2 ohms, repair as necessary. After repairs, go to step 13). If circuit is 2 ohms or less, go to step 10).
  8. Check for poor sensor ground circuit terminal connection at Bank 2 HO2S 1 harness connector. Repair or replace terminal as necessary. After repairs, go to step 13). If terminals are okay, go to step 11).
  9. Check for poor sensor ground terminal connection at PCM harness. Repair or replace terminals as necessary. After repairs, go to step 13). If terminals are okay, go to step 12).
  10. Check for poor signal circuit terminal connection at PCM harness. Repair or replace terminals as necessary. After repairs, go to step 13). If terminals are okay, go to step 12).
  11. Replace Bank 1 HO2S 1 sensor. After replacing oxygen 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. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0154. 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Oxygen supply inside HO2S is necessary for its proper operation. This supply of oxygen is provided through HO2S wires. Inspect all wires and terminals for breaks or contamination.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. Go to next step. NOTE: If engine has been operating, allow engine to cool for about one hour before proceeding with tests.
  2. Turn ignition off. Turn ignition, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage goes from bias voltage to more than 700 mV or less than 300 mV, see DIAGNOSTIC AIDS. If HO2S voltage remains within 300-700 mV range, go to next step.
  3. Check HO2S ignition feed fuse. If fuse is faulty, go to step 11). If fuse is okay, go to next step.
  4. Raise and support vehicle. Disconnect HO2S harness connector. Connect test light to chassis ground and probe ignition feed circuit at HO2S harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
  5. Connect test light between ignition feed and heater ground at HO2S harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  6. Using DVOM, check resistance between ignition feed and heater ground at HO2S harness connector. If resistance is 3.5-14.0 ohms, go to step 9). If resistance is not as specified, go to step 10).
  7. Repair open in HO2S ignition feed circuit. After repairs, go to step 12).
  8. Repair open in HO2S heater ground circuit. After repairs, go to step 12).
  9. Check for poor terminal connection at HO2S connector. Repair or replace terminals. After repairs, go to step 12).
  10. Replace HO2S. After replacing HO2S, go to step 12).
  11. Locate and repair short to ground in HO2S ignition feed circuit and replace fuse. After repairs, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0155. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data may aid in locating intermittent condition. If DTC cannot be duplicated, information included in this data can be useful in determining how many miles since DTC has set.

FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.) that are noted. This will isolate when DTC failed.

HO2S heater diagnostic will only run on a cold start and will only once per ignition cycle. Oxygen supply inside HO2S is necessary for proper operation and is provided through HO2S wires. Check all HO2S wires and connections for breaks or contamination.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Operate vehicle under following parameters; engine coolant temperature at more than 118°F (48°C), system in closed loop, fuel trim enabled, air/fuel ratio 14.6:1-14.8:1, TP sensor angle between 3-20 percent, and HO2S signal at less than 39 mV for 38 seconds. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If voltage is less than 39 mV, go to step 4). If voltage is not less than 39 mV, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0157. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect HO2S harness connector. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S low circuit. If voltage is within a range of 375-525 mV, see DIAGNOSTIC AIDS. If not, go to next step.
  5. Turn ignition off. Disconnect PCM harness connector. Check HO2S circuit for short to ground or short to sensor ground circuit. Repair as necessary. After repairs, go to next step. If circuit is okay, go to step 7).
  6. Repair HO2S 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, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Then, select DTC, SPECIFIC and enter DTC P0157. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If test does not run or failed, repeat step 2).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If other undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

Check HO2S wires grounding against exhaust manifold. Oxygen supply inside HO2S is necessary for its proper operation. This supply of oxygen is provided through HO2S wires. Inspect all wires and terminals for breaks or contamination.

Check for lean fuel injector(s) or low fuel pressure. Perform injector balance test. See the SYSTEM/COMPONENT TESTS article. Check for fuel contamination. Water can cause a lean condition and can set a DTC. Check for exhaust leaks near HO2S, vacuum or crankcase leaks that can cause a lean condition. Check for faulty oxygen sensor.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Increase engine speed to about 1200 RPM. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S display. If voltage is more than 930 mV, go to step 4). If voltage is as specified, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0158. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Remove HO2S heater fuse. Monitor HO2S voltage. If voltage drops to within a range of 375-525 mV, go to next step. If voltage is not as specified, go to step 7).
  5. Reinstall fuse. Disconnect HO2S harness connector. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S low signal circuit. If voltage is within a range of 375-525 mV, go to step 10). If voltage is not as specified, go to next step.
  6. With jumper wire still connected, remove HO2S heater fuse. Monitor HO2S voltage on scan tool. If voltage is within a range of 375-525 mV, go to step 9). If voltage is not as specified, go to step 8).
  7. Turn ignition off. Disconnect HO2S signal circuit at PCM connector. Disconnect HO2S harness connector. Turn ignition on. Using DVOM, check voltage on HO2S sensor signal circuit at PCM harness connector. If voltage is present, go to next step. If voltage is not present, see DIAGNOSTIC AIDS.
  8. Repair short to voltage in HO2S signal circuit between sensor and PCM. After repairs, go to step 12).
  9. Repair shorted HO2S signal circuit and HO2S heater battery supply circuit. After repairs, go to next step. If repair is not necessary or if circuits are okay, go to step 11).
  10. Replace HO2S. After replacing HO2S, go to step 12).
  11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Then, select DTC, SPECIFIC and then enter DTC P0158. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If test does not run or failed, repeat step 2).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If other undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

Check HO2S wires grounding against exhaust manifold. Oxygen supply inside HO2S is necessary for its proper operation. This supply of oxygen is provided through HO2S wires. Inspect all wires and terminals for breaks or contamination.

Check for rich fuel injector(s) or too high fuel pressure. Perform injector balance test. See the SYSTEM/COMPONENT TESTS article. Check for saturated EVAP canister or incorrectly installed MAF sensor. Disconnect MAF sensor and observe if rich condition is corrected. Check for leaking fuel pressure regulator or leaking regulator vacuum hose. Check TP sensor. An intermittent TP sensor output will cause system to go rich.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Increase engine speed to more than 1200 RPM for 2 minutes. Using scan tool, select ENGINE 1 DATA LIST and monitor Bank 2 HO2S 2 voltage. If voltage is varying outside a range of 391-491 mV, go to next step. If not, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0160. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition on, with engine off. Disconnect Bank 2 HO2S 2 harness connector. Connect a fused jumper wire between ground and PCM connector (harness side) HO2S high and low signal circuits. If voltage is less than 200 mV, go to step 8). If voltage is more than 200 mV, go to next step.
  5. Remove jumper wire. Using DVOM, check voltage between sensor high and heater ground circuit, on PCM harness side. If voltage is more than 375 mV, go to next step. If not, go to step 7).
  6. Turn ignition off. Disconnect PCM harness connector. Check resistance of bank 2 HO2S 2 low circuit. If resistance is more than 2 ohms, repair as necessary. After repairs, go to step 13). If resistance is 2 ohms or less, go to step 9).
  7. Turn ignition off. Disconnect PCM harness connector. Check resistance of Bank 1 HO2S 1 signal circuit. If resistance is more than 2 ohms, repair as necessary. After repairs, go to step 13). If resistance is 2 ohms or less, go to step 10).
  8. Check low circuit signal terminal for poor connection at Bank 2 HO2S 2 harness connector. Repair or replace terminal as necessary. After repairs, go to step 13). If terminals are okay, go to step 11).
  9. Check low signal terminal for poor connection at PCM harness. Repair or replace terminals as necessary. After repairs, go to step 13). If terminals are okay, go to step 12).
  10. Check signal circuit terminal for poor connection at PCM harness. Repair or replace terminals as necessary. After repairs, go to step 13). If terminals are okay, go to step 12).
  11. Replace Bank 2 HO2S 2 sensor. After replacing oxygen 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. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0160. 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Oxygen supply inside HO2S is necessary for its proper operation. This supply of oxygen is provided through HO2S wires. Inspect all wires and terminals for breaks or contamination.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If engine has been operating, allow engine to cool for about 1 hour before proceeding with tests.
  2. Turn ignition off. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage goes from bias voltage to more than 700 mV or less than 300 mV, see DIAGNOSTIC AIDS. If HO2S voltage does not go from bias voltage to less than 300 mV or more than 700 mV, go to next step.
  3. Check HO2S ignition feed fuse. If fuse is faulty, go to step 11). If fuse is okay, go to next step.
  4. Raise and support vehicle. Disconnect HO2S harness connector. Connect test light to chassis ground and probe ignition feed circuit at HO2S harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
  5. Connect test light between ignition feed circuit and heater ground at HO2S harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  6. Using DVOM, check resistance between ignition feed and heater ground at HO2S harness connector. Resistance should be 3.5-14.0 ohms. If resistance is as specified, go to step 9). If resistance is not as specified, go to step 10).
  7. Repair open in HO2S ignition feed circuit. After repairs, go to step 12).
  8. Repair open in HO2S heater ground circuit. After repairs, go to step 12).
  9. Check for poor terminal connection at HO2S connector. Repair or replace terminals. After repairs, go to step 12).
  10. Replace HO2S. After replacing HO2S, go to step 12).
  11. Locate and repair short to ground in HO2S ignition feed circuit and replace fuse. After repairs, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0161. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data may aid in locating intermittent condition. If DTC cannot be duplicated, information included in this data can be useful in determining how many miles since DTC has set.

FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.) that are noted. This will isolate when DTC failed.

HO2S heater diagnostic will only run once on a cold start and only once per ignition cycle. Oxygen supply inside HO2S is necessary for proper operation and is provided through HO2S wires. Check all HO2S wires and connections for breaks or contamination.

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 long and short term fuel trim values.

Short term fuel trim values change rapidly in response to HO2S signal voltages. These changes fine tune engine fueling. Long term fuel trim values changes in response to trends in short term fuel trim. Long term fuel trim makes coarse adjustments to fueling in order to re-center and restore control to short term fuel trim. Long term and short term fuel trim can be monitored by use of scan tool.

Ideal fuel trim value is about zero percent. A positive fuel trim indicates that PCM is adding fuel to compensate for a lean condition. A negative fuel trim indicates that PCM is reducing amount of fuel to compensate for rich condition. DTC will set if PCM detects an excessively rich or lean condition.

DTC will set when following conditions are present

  1. DTCs P0100, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0220, P0221, P0225, P0226, P0300, P0335, P0336, P0351-P0358, P0372, P0410, P0412, P0418, P0430, P0441, P0443, P0500, P0501, P0503, P0601, P1111, P1112, P1120, P1121, P1125, P1133, P1153, P1220, P1221, P1258, P1351, P1361, P1371, P1415, P1416, P1441, P1514, P1515, P1516 or P1517 not set.
  2. Engine coolant temperature 120-239°F (60-115°C).
  3. Fuel system operating in closed loop.
  4. Fuel trim enabled.
  5. MAP 20-90 kPa.
  6. EVAP canister purge not enabled or EVAP canister purge duty cycle more than 75 percent.
  7. PCM detects average long term fuel trim cell values are more than a predetermined threshold.
  8. BARO more than 70 kPa.
  9. MAF 5-100 gm/s.
  10. IAT -22 to 302°F (-22 to 150°C).
  11. Engine speed 500-4000 RPM.
  12. TP sensor angle less than 75 percent.
  13. Vehicle speed less than 75MPH.
  14. Conditions met for 10 seconds.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If other DTC(s) are present, except P0174, diagnose affected DTC(s) first.
  2. Start and warm engine to normal operating temperature. Ensure system is in "closed loop". Using scan tool, select FUEL TRIM DATA LIST and monitor LT FT BN 1, and ST FT BN 1. If LT FT is less than 22 percent, or ST FT reads less than 10 percent, go to next step. If values are not as specified, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0171. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. If DTC P0174 is also present, go to next step. If DTC P0174 is not present, go to step 6).
  5. Check vacuum hoses for splits, kinks and proper routing. MAF sensor, air induction system, throttle Body, intake manifold, PCV system and EGR valve for vacuum leaks. Check for fuel contamination. Check for good PCM and sensor grounds. Check engine mechanical condition. Repair as necessary. After repairs, go to step 7). If engine mechanical repairs are not necessary, diagnose fuel system. See the SYSTEM/COMPONENT TESTS article.
  6. Check bank 1 for exhaust leaks or loose exhaust hardware. Ensure oxygen sensor is properly installed. Check vacuum leaks that will affect bank 1 only. Check engine mechanical condition. After repairs, go to next step. If repairs are not necessary, diagnose fuel system. See the SYSTEM/COMPONENT TESTS article.
  7. Repair or replace any faulty items. After repairs, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0171. Operate vehicle within conditions that set 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

If DTC P0171 cannot be duplicated, problem could have been caused by engine running out of fuel. A fuel delivery malfunction will cause DTC to set. Check all items that can cause a lean condition.

PCM monitors oxygen sensor signal voltage and adjusts fuel delivery based on signal voltage. A change made to fuel delivery is indicated by long and short term fuel trim values.

Short term fuel trim values change rapidly in response to HO2S signal voltages. These changes fine tune engine fueling. Long term fuel trim values changes in response to trends in short term fuel trim. Long term fuel trim makes coarse adjustments to fueling in order to re-center and restore control to short term fuel trim. Long term and short term fuel trim can be monitored by use of scan tool.

Ideal fuel trim value is about zero percent. A positive fuel trim indicates that PCM is adding fuel to compensate for a lean condition. A negative fuel trim indicates that PCM is reducing amount of fuel to compensate for rich condition. DTC will set if PCM detects an excessively rich or lean condition.

DTC will set when following conditions are present

  1. DTCs P0100, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0220, P0221, P0225, P0226, P0300, P0335, P0336, P0351-P0358, P0372, P0410, P0412, P0418, P0430, P0441, P0443, P0500, P0501, P0503, P0601, P1111, P1112, P1120, P1121, P1125, P1133, P1153, P1220, P1221, P1258, P1351, P1361, P1371, P1415, P1416, P1441, P1514, P1515, P1516 or P1517 not set.
  2. Engine coolant temperature 120-239°F (60-115°C).
  3. Fuel system operating in closed loop.
  4. Fuel trim enabled.
  5. MAP 20-90 kPa.
  6. EVAP canister purge not enabled or EVAP canister purge duty cycle more than 75 percent.
  7. PCM detects average long term fuel trim cell values are more than a predetermined threshold.
  8. BARO more than 70 kPa.
  9. MAF 5-100 gm/s.
  10. IAT -22 to 302°F (-22 to 150°C).
  11. Engine speed 500-4000 RPM.
  12. TP sensor angle less than 75 percent.
  13. Vehicle speed less than 75MPH.
  14. Conditions met for 10 seconds.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If other DTC(s) are present, except P0175, diagnose affected DTC(s) first.
  2. Start and warm engine to normal operating temperature. Ensure system is in "closed loop" operation. Using scan tool, select FUEL TRIM DATA LIST and monitor LT FT BN 1, and ST FT BN 1. If LT FT is more than -14 percent, or ST FT reads more than -10 percent, go to next step. If not more than specification, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0172. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. If DTC P0175 is also present, go to next step. If DTC P0175 is not present, go to step 6).
  5. Check for collapsed air intake duct, restricted fuel filter, improperly installed MAF sensor, foreign objects in MAF sensor inlet or for fuel in fuel regulator hose. Repair as necessary. After repairs, go to step 7). If components are okay, or repair is not necessary, diagnose fuel system. See the SYSTEM/COMPONENT TESTS article.
  6. Check for leaking fuel injector(s) in bank 1. Repair or replace as necessary. After repairs, go to step 9). If injector(s) are okay, go to step 8).
  7. Replace or repair affected components. After repairs, go to step 9).
  8. Replace faulty HO2S. After replacing oxygen sensor, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0172. Operate vehicle within conditions that set 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

For intermittent problem, see the TESTS W/O CODES article.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If other DTC(s) are present, except for P0171, diagnose other DTC(s) first.
  2. Start and warm engine to normal operating temperature. Ensure system is in "closed loop". Using scan tool, select FUEL TRIM DATA LIST and monitor LT FT BN 2, and ST FT BN 2. If LT FT BN 2 is less than 22 percent, or ST FT BN 2 is less than 10 percent, go to next step. If displayed value is not less than specification, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0174. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. If DTC P0171 is also present, go to next step. If DTC P0171 is not present, go to step 6).
  5. Check vacuum hoses for splits, kinks and proper routing. Check for vacuum leaks at throttle Body, intake manifold, EGR valve or MAF sensor. Check for fuel contamination. Check for engine mechanical failure. Repair problem as necessary. After repairs, go to step 7). If problem is not found or repair is not necessary, diagnose fuel system. See the SYSTEM/COMPONENT TESTS article.
  6. Inspect bank 2 for exhaust leaks, missing or loose hardware. Check if bank 2 HO2S is installed properly and if connectors are secured. Check vacuum leaks that will only affect bank 1. Check engine mechanical condition. Repair problem as necessary. After repairs, go to next step. If problem is not found or repair is not necessary, diagnose fuel system. See the SYSTEM/COMPONENT TESTS article.
  7. Repair or replace affected faulty components. After repairs or replacement, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0174. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If DTC cannot be duplicated, DTC may have been set by engine running out of fuel. A fuel delivery malfunction will also cause DTC to set. Inspect related items that can cause a lean condition.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If other DTC(s) are present, except P0172, diagnose other DTC(s) first.
  2. Start and warm engine to normal operating temperature. Ensure system is in "closed loop". Using scan tool, select FUEL TRIM DATA LIST and monitor LF FT BN 2, and ST FT BN 2. If LT FT BN 2 is more than -14 percent, or ST FT BN 2 display is more than -10 percent, go to next step. If displayed value is not more than specification, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0175. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. If DTC P0172 is also present, go to next step. If DTC P0172 is not present, go to step 6).
  5. Check for collapsed air intake duck, restricted air filter, improperly mounted MAF sensor, foreign objects blocking inlet screen or for fuel in pressure regulator hose. Repair as necessary. After repairs, go to step 7). If problem is not found or repairs are not necessary, diagnose fuel system. See the SYSTEM/COMPONENT TESTS article.
  6. Check for leaking fuel injector(s) in bank 2. If injector(s) are leaking, go to step 9). If injector(s) are okay, go to step 8).
  7. Repair or replace affected components. After repairs, go to step 9).
  8. Replace faulty HO2S. After replacing HO2S, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0175. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If problem is intermittent, see the TESTS W/O CODES article.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Using scan tool, select MISFIRE DATA LIST and monitor all MISFIRE CUR. COUNTERS (1 counter per cylinder). If any of counters are incrementing, go to step 4). If counters are not incrementing, go to next step.
  3. Using scan tool, select MISFIRE DATA LIST and monitor MISFIRE HIST. COUNTERS. If counter indicates 0.0 counts, perform DTC P1222 diagnostic test. If counter does not indicate 0.0 counts, see DIAGNOSTIC AIDS.
  4. Check injector fuse. If fuse is okay, go to next step. If fuse is faulty, go to step 8).
  5. Turn ignition off. Disconnect harness connector to affected injectors. Turn ignition on. Using a test light connected to ground, probe injector harness connector ignition feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10).
  6. Turn ignition off. Connect injector test light to affected injector harness connector. Start and operate engine at idle. If injector test light flashes, go to next step. If injector test light does not flash, go to step 11).
  7. Inspect injector harness terminals. Repair as necessary. After repairs, go to step 17). If injector terminals are okay, go to step 15).
  8. Turn ignition off. Disconnect all injector harness connectors related to fuse that is faulty. Connect test light to battery positive. Probe injector feed circuits of one of disconnected injector harnesses. If test light illuminates, go to step 13). If test light does not illuminate, go to next step.
  9. Using DVOM, check resistance of each injector related to fuse that is faulty. If resistance is less than 11.6 ohms, go to step 15). If injector resistance is not less than as specified, go to step 14).
  10. Repair injector ignition feed circuit to affected injector. After repairs, go to step 17).
  11. Turn ignition off. Disconnect PCM harness connector. Check for open in injector driver circuit to PCM connector. If circuit is open, go to next step. If circuit is okay, go to step 16).
  12. Repair open in injector driver circuit. After repairs, go to step 17).
  13. Repair grounded ignition feed circuit to injectors. After repairs, go to step 17).
  14. Repair intermittent short to ground in injector ignition feed circuit. After repairs, go to step 17).
  15. Replace faulty injector(s). After replacing injector(s), go to step 17).
  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 P0200. 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).
  18. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If an injector is disconnected while engine is operating and if DTC P0200 is present, injector driver will be disabled for entire ignition cycle. When injector driver is disabled, engine misfire will be apparent and a misfire related DTC will set.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If other DTC(s), except P0131, P0132, P0133, P0151, P0152, P0153, P0171, P0172, P0174, P0175, P1133, P1135, P1136, P1153, P1155 or P1156 are present, diagnose affected DTC(s) first.
  2. Start and operate engine at idle. Using scan tool, select MISFIRE DATA LIST function and monitor MISFIRE CUR. COUNTERS (one counter per cylinder). If any of misfire counter is incrementing, go to next step. If misfire counter is not incrementing, go to step 4).
  3. If only one cylinder is misfiring, go to step 5). If more than one of cylinders is misfiring, check vacuum hoses for splits, kinks and proper routing. Check for leaks at throttle Body, intake manifold, EGR valve or PCV system. Check PCM grounds for proper connection. Check that all injector harness connectors are connected to proper injector/cylinder. Repair as necessary. After repairs, go to step 19). If components are okay, or repair is not necessary, go to step 5).
  4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0300. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  5. Turn ignition off. Disconnect ignition coil wire from distributor. Install Spark Tester (J-26792) to coil wire. Crank engine. If spark is present, go to next step. If spark is not present, reconnect coil wire and go to step 12).
  6. Disconnect spark plug wire to affected cylinder. Connect spark tester to spark plug wire. Crank engine. If spark is present, go to next step. If spark is not present, go to step 15).
  7. Remove and check spark plug from affected cylinder. If spark plug is okay, go to next step. If spark plug is fouled, go to step 9).
  8. Swap spark plug to another cylinder that is operating properly. Operate vehicle under same conditions that misfire occurred. If misfire moved with spark plug, go to step 17). If misfire is still present at original cylinder, perform fuel injector coil test. See the SYSTEM/COMPONENT TESTS article.
  9. If spark plug is fouled with oil or coolant, diagnose mechanical engine problem. If spark plug is not fouled, go to next step.
  10. Check spark plug for signs of cracks, wear or improper gap. If spark plug is faulty, go to next step. If spark plug is okay, go to step 18).
  11. Replace or re-gap spark plug. After replacing or re-gapping spark plug, go to step 19).
  12. Using DVOM, check coil wire resistance. If resistance is less than 10,000 ohms, go to next step. If not, go to step 14).
  13. Replace ignition coil. After replacing ignition coil, go to step 19).
  14. Replace coil wire. After replacing coil wire, go to step 19).
  15. Using DVOM, check spark plug wire to affected cylinder(s). If resistance is greater 10,000 ohms, go to next step. If not, go to step 17).
  16. Replace faulty spark plug wire(s). After replacing spark plug wire(s), go to step 19).
  17. Replace faulty spark plug(s). After replacing spark plug(s), go to step 19).
  18. Check distributor for carbon tracking, contamination, moisture or physical damage. Replace as necessary. If problem is corrected, go to next step. If problem is still present, check engine for mechanical problems.
  19. If complaint is due to MIL flashing, perform DTC P0420 or P0430 test. If MIL is not flashing, go to next step.
  20. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0300. 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).
  21. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

A misfire could be caused by excessive vibration from sources other that engine. Check following for possible cause, tire/wheel out of balance/round, uneven brake rotor or drum surface, or a rough road condition. If problem is intermittent, see the TESTS W/O CODES article.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGN under DTC status for DTC(s) P0327 and P1371. If DTC P0372 or P1371 failed in this ignition cycle, go to applicable/affected DTC. If DTC P0372 or P1371 does not fail in this ignition cycle, go to next step.
  3. Using scan tool, select ENGINE SPEED and observe display while moving related harness connectors (at component and PCM). Also, observe for engine miss or stall when a connector is moved. If display changes abruptly, or engine misses or stalls while moving connectors, go to step 6). If no changes are noticed while moving connectors, go to next step.
  4. Using scan tool, select ENGINE SPEED and observe scan tool display while moving related harness connectors (at component and PCM). Also, observe for engine miss or stall when a connector is moved. If display changes abruptly, or engine misses or stalls while moving connectors, go to step 7). If no changes are noticed while moving connectors, go to next step.
  5. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0323. If scan tool indicates that this test failed this ignition, go to step 8). If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  6. Repair affected connectors or terminals. After repairs, go to step 9).
  7. Repair faulty wiring. After repairs, go to step 9).
  8. Recheck all affected circuits and connectors. If circuits and connectors are okay, check ignition distributor. Replace or repair as necessary and then go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0323. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

When DTC P0323 is present, a misfire may be apparent. To locate intermittent problem, use scan tool's snapshot feature. Try to duplicate conditions under which misfire is present. When reviewing data, watch for any abnormal high and low resolution timing pulses.

  1. Perform Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Ensure engine mechanical problem is not causing knock. Start and warm engine to normal operating temperature. Using scan tool select DTC, SPECIFIC function, then enter DTC P0325. If scan tool indicates that this diagnostic failed this ignition, go to next step. If scan tool does not indicate that this diagnostic failed this ignition, go to step 4).
  3. Turn ignition off. Check PCM for missing KS module, module not being fully seated or incorrect installation. Repair as necessary. After repairs, go to step 6). If no problems are found, go to next step.
  4. Replace KS module. Start and warm engine to normal operating temperature. Using scan tool, select DTC, SPECIFIC function, then enter DTC P0325. If scan tool indicates that this diagnostic failed this ignition, go to next step. If scan tool does not indicate that this diagnostic failed this ignition, go to step 6).
  5. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0325. 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).
  7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If diagnostic test does not run, check if KS module is missing or faulty KS module circuit. Check KS module terminals for corrosion. If corrosion is present, check module access cover seal for cuts or nicks.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Ensure engine mechanical problem is not causing knock. Start and warm engine to normal operating temperature. Using scan tool, monitor KS activity. If scan tool indicates YES, go to step 4). If scan tool does not indicate YES, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0332. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Disconnect KS harness connector. Using DVOM, check voltage between KS signal circuit and ground. If voltage reading is 5 volts, go to next step. If not, go to step 8).
  5. Using DVOM, check resistance between KS and engine block. If resistance is 93,000-107,000 ohms, go to next step. If not, go to step 9).
  6. Turn ignition off. Connect DVOM between KS and ground. Set DVOM to AC voltage scale. Tap on engine while observing signal on DVOM. If any signal is present, go to next step. If signal is not present, go to step 9).
  7. Check KS signal circuit for poor terminal connection at KS. Repair as necessary. After repairs, go to step 12). If terminal connections are okay, go to step 10).
  8. Turn ignition off. Disconnect PCM harness connector. Turn ignition on and 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 12). If circuit is okay, go to step 10).
  9. Replace KS. After replacing KS, go to step 12).
  10. Turn ignition off. Disconnect PCM harness connector. Check KS signal circuit for proper terminal connection at PCM. Repair or replace terminals. After repairs, go to step 12). If terminals are okay, go to next step.
  11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0332. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Check KS for proper connection. A loose or over-torqued KS can cause DTC to set.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. If DTC P1371 or P1373 is also present, diagnose affected DTC first. If DTC(s) are not present, go to next step.
  3. Start engine. Using scan tool, monitor CRANKSHAFT RPM. If RPM is indicated, go to next step. If RPM is not indicated, go to step 9).
  4. Using scan tool, monitor CKP:LO RES ANGLE. Actual value may fluctuate, but should remain within range. If value is within range of -10 DEV to +7 DEV, go to step 7). If value is not within range, go to next step.
  5. While observing CKP:LO RES ANGLE, quickly increase engine RPM once and allow to return to idle. If range changes from a positive value on acceleration to a negative value on deceleration, go to step 15). If value does not change, go to next step.
  6. If value is fixed or out of range, go to step 16). If value is as specified, go to next step.
  7. Using scan tool, select MISFIRE DATA LIST and monitor CYL MODE MISFIRE INDEX with engine at idle. Misfire index value should read 1000. If value is not as specified, go to next step. If value is as specified, go to step 12).
  8. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0335. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  9. Turn ignition on, with engine off. Disconnect CKP sensor harness connector. Connect a test light between ground and CKP sensor ignition feed circuit at harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 17).
  10. Connect test light between CKP sensor harness connector terminals "A" and "B". If test light illuminates, go to next step. If test light does not illuminate, go to step 19).
  11. Install Signal Generator Tester (J 33431-B) to CKP sensor harness connector and ground. Turn ignition on. Turn tester on and set to generate a 54 MPH signal. Using scan tool, monitor crankshaft RPM. If scan tool indicates crankshaft RPM is present, go to step 17). If crankshaft RPM is not indicated, go to step 13).
  12. Visually inspect CKP sensor for physical damage, loose or improper installation, wiring routed too close to secondary ignition components or poor connections/terminal contact at sensor or PCM. Repair as necessary. After repairs, go step 23). If components and circuits are okay, go to step 21).
  13. Turn ignition off. Disconnect PCM connector. Using DVOM, check continuity to signal circuit from sensor harness connector to PCM connector. If continuity is present, go to next step. If continuity is not present, go to step 20).
  14. Using DVOM, check resistance between signal circuit and ground. If resistance is infinite, go to step 22). If resistance is not infinite, go to step 20).
  15. Check excessive timing gear/chain wear. Repair as necessary. After repairs, go to step 23).
  16. Check for poor connections/terminal at CKP sensor or for proper reluctor wheel installation. Repair as necessary. After repairs, go to step 23).
  17. Check for poor connections/terminal tension at CKP sensor. Repair as necessary. After repairs, go to step 23). If connection or terminal tension is okay, go to step 21).
  18. Repair ignition feed circuit. After repairs, go to step 23).
  19. Repair ground circuit. After repairs, go to step 23).
  20. Repair signal circuit. After repairs, go to step 23).
  21. Replace CKP sensor. After replacing sensor, go to step 23).
  22. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  23. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0335. 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).
  24. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Check for poor connections/terminal tension at CKP sensor. Check for excessive timing gear/chain tension, excessive distributor drive backlash, damaged crankshaft reluctor wheel or for improper installation. Check engine front cover assembly for damage or sensor coming in contact with reluctor wheel.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. If DTC P1371 or P1373 is also present, diagnose affected DTC first. If DTC(s) are not present, go to next step.
  3. Start engine. Using scan tool, monitor CRANKSHAFT RPM. If RPM is indicated, go to next step. If RPM is not indicated, go to step 9).
  4. Using scan tool, monitor CKP:LO RES ANGLE. Actual value may fluctuate, but should remain within range. If value is within range of -10 DEV to +7 DEV, go to step 7). If value is not within range, go to next step.
  5. While observing CKP:LO RES ANGLE, quickly increase engine RPM once and allow to return to idle. If range changes from a positive value on acceleration to a negative value on deceleration, go to step 14). If value does not change, go to next step.
  6. If value is fixed or outside of -10 DEV to +7 DEV range, go to step 15). If value is as specified, go to next step.
  7. Using scan tool, select MISFIRE DATA LIST and monitor CYL MODE MISFIRE INDEX with engine at idle. Misfire index value should read 1000. If value is not as specified, go to next step. If value is as specified, go to step 12).
  8. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0336. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  9. Turn ignition on, with engine off. Disconnect CKP sensor harness connector. Connect a test light between CKP sensor ignition feed circuit to battery ground at harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 17).
  10. Connect test light between CKP sensor harness connector terminals "A" and "B". If test light illuminates, go to next step. If test light does not illuminate, go to step 18).
  11. Install Signal Generator Tester (J 33431-B) to CKP sensor harness connector and ground. Turn ignition on. Turn tester on and set to generate a 54 MPH signal. Using scan tool, monitor crankshaft RPM. If scan tool indicates that crankshaft RPM is present, go to step 16). If crankshaft RPM is not indicated, go to step 13).
  12. Visually inspect CKP sensor for physical damage, loose or improper installation, wiring routed too close to secondary ignition components or poor connections/terminal contact at sensor or PCM. Repair as necessary. After repairs, go step 22). If components or circuits are okay, go to step 20).
  13. Turn ignition off. Disconnect PCM connector. Using DVOM, check continuity to signal circuit from sensor harness connector to PCM connector. If continuity is present, go to step 21). If continuity is not present, go to step 19).
  14. Check excessive timing gear/chain wear. Repair as necessary. After repairs, go to step 22).
  15. Check for poor connections/terminal at CKP sensor or for proper reluctor wheel installation. Repair as necessary. After repairs, go to step 22).
  16. Check for poor connections/terminal tension at CKP sensor. Repair as necessary. After repairs, go to step 22). If connection or terminal tension is okay, go to step 20).
  17. Repair ignition feed circuit. After repairs, go to step 22).
  18. Repair ground circuit. After repairs, go to step 22).
  19. Repair signal circuit. After repairs, go to step 22).
  20. Replace CKP sensor. After replacing sensor, go to step 22).
  21. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  22. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0336. 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).
  23. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Check for poor connections/terminal tension at CKP sensor. Check for excessive timing gear/chain tension, excessive distributor drive backlash, damaged crankshaft reluctor wheel or for improper installation. Check engine front cover assembly for damage or sensor coming in contact with reluctor wheel.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Using scan tool, monitor high resolution signal. If scan tool displays signal as inactive, go to step 4). If scan tool displays signal as active, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0372. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect ignition system test connector. Turn ignition on. Using DVOM, check voltage on terminal "B" at PCM side of ignition test connector. If voltage is 5 volts, go to next step. If voltage is not as specified, go to step 8).
  5. Turn ignition off. Reconnect ignition test connector. Disconnect distributor connector. Turn ignition on. Using DVOM, check voltage on terminal "B" of distributor harness connector. If voltage is about 5 volts, go to step 11). If voltage is not as specified, go to next step.
  6. If voltage is more than 5 volts, go to next step. If voltage is less than 5 volts, go to step 12).
  7. Repair short to voltage on high resolution signal circuit to ignition test connector. After repairs, go to step 14).
  8. If voltage is more than 5 volts, go to step 10). If voltage is less than 5 volts, go to next step.
  9. Repair open or grounded high resolution circuit from ignition test connector to PCM. After repairs, go to step 14). If circuit is okay, go to step 13).
  10. Repair short to voltage on high resolution signal circuit from ignition test connector to distributor. After repairs, go to step 14).
  11. Repair faulty distributor connection or faulty distributor. After repairs, go to step 14).
  12. Repair open or grounded high resolution circuit from ignition test connector to distributor. After repairs, go to step 14). If circuit is okay, go to next step.
  13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, 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 DTC P0372. 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).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If DTC P1351 and/or P1361 is present with P0372, and no external fault can be found, replace PCM. If only DTC P0372 is present and distributor connections are okay, replace distributor. If distributor components are replaced, check distributor vent system.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and warm engine to normal operating temperature. Using scan tool, command EGR duty cycle to 100 percent and then back to zero percent. If engine RPM changes (decreases or runs rough) when EGR is commanded to 100 percent, go to next step. If engine RPM does not change when EGR is commanded to 100 percent, go to step 4).
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0400. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Manually lift EGR valve diaphragm. If engine RPM changes (decrease or run rough), go to next step. If engine RPM does not change, go to step 10).
  5. Disconnect harness at solenoid. Connect vacuum gauge to manifold side of vacuum harness and check vacuum supply to valve. Increase engine speed to about 2000 RPM. If vacuum reading is at least 7 in. Hg, go to next step. If not, go to step 11).
  6. Turn engine off. Rotate vacuum harness and connect only manifold side of vacuum harness to solenoid. Connect vacuum gauge to other port of solenoid. Using scan tool, command EGR solenoid ON and OFF while observing vacuum gauge. If vacuum gauge indicates that vacuum is present when solenoid is on and bleed off when solenoid is off, go to next step. If vacuum is not present, go to step 13).
  7. Reconnect vacuum hoses to solenoid. Using scan tool, command EGR solenoid ON and OFF. If vacuum is indicated when commanded, go to next step. If vacuum is not indicated when commanded, go to step 12).
  8. Turn ignition off. Apply vacuum to EGR valve and observe EGR valve diaphragm. EGR valve should move freely and hold vacuum for at least 20 seconds. If EGR valve is free and holds vacuum, go to next step. If EGR valve does not hold vacuum, go to step 14).
  9. Connect vacuum gauge between EGR and EGR solenoid. Apply 10 in. Hg to EGR solenoid. Start engine and observe vacuum gauge. Vacuum should drop while engine is started and EGR valve should move to seated position. If EGR solenoid operates as specified, go to step 15). If EGR does not operate as specified, go to step 14).
  10. Repair plugged or restricted EGR passages. After repairs, go to step 16).
  11. Repair plugged vacuum port or vacuum line. After repairs, go to step 16).
  12. Repair or replace faulty vacuum line to EGR valve. After repairs, go to step 16).
  13. Replace EGR solenoid. After replacing solenoid, go to step 16).
  14. Replace EGR valve. After replacing EGR valve, go to step 16).
  15. Check for partially clogged EGR passages, restricted or damaged EGR pipe, or modified or faulty exhaust system components. Repair or replace as necessary. After repairs, 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 DTC P0400. 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).
  17. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Suction from shop exhaust hose can alter backpressure and may alter operation of EGR valve during in-stall testing. DTC can set if exhaust system is leaking. Check vacuum lines for leaks and proper routing.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command EGR solenoid on and off. If solenoid turns on and off as commanded, go to next step. If solenoid does not respond as commanded, go to step 5).
  3. Turn ignition off. Disconnect PCM harness connector containing solenoid control circuit. Turn ignition on. Using DVOM, set DVOM to 10-amp scale. Check current from solenoid control circuit in PCM harness connector to ground for 2 minutes. If current draw is less than .75 amp (but not zero amps), see DIAGNOSTIC AIDS. If not, go to next step.
  4. Turn ignition off. Disconnect EGR solenoid. Using DVOM, check resistance from solenoid control circuit in PCM harness connector and ground. If resistance is infinite, go to step 12). If resistance is not as infinite, go to step 10).
  5. Turn ignition off. Disconnect EGR solenoid. Connect test light between solenoid harness connectors. Turn ignition on. Using scan tool, command 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.
  6. Connect test light to ground and probe ignition feed circuit in solenoid harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
  7. Turn ignition off. Reconnect EGR solenoid. Disconnect PCM connector containing solenoid control circuit. Turn ignition on. Connect a fused jumper wire between ground and PCM connector (harness side), solenoid control circuit. If solenoid operates, go to step 9). If solenoid does not operate, go to step 10).
  8. Check connections at EGR solenoid. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 12).
  9. Check connections at PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 13).
  10. Repair faulty EGR solenoid control circuit. After repairs, go to step 14).
  11. Repair faulty EGR solenoid ignition feed circuit. After repairs, go to step 14).
  12. Replace EGR solenoid. After replacing EGR solenoid, 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. Warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0403. 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).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, enable AIR pump. If pump turns on, go to step 6). If AIR pump does not turn on, go to next step.
  3. Turn ignition off. Disconnect AIR pump relay. Turn ignition on, engine off. Using test light connected to ground, probe power supply circuit to relay. If test light illuminates, go to next step. If test light does not illuminate, go to step 14).
  4. Turn ignition off. Reconnect AIR pump relay. Disconnect electrical connector from AIR pump. Connect test light to battery negative terminal and probe AIR pump harness connector terminal "A". Turn ignition on, with engine off. Using scan tool, enable AIR pump. If test light illuminates, go to next step. If test light does not illuminate, go to step 22).
  5. Connect test light between AIR pump harness connector terminals "A" and "C". Using scan tool, enable AIR pump. If test light illuminates, go to step 31). If test light does not illuminate, go to step 23).
  6. Turn ignition off. Disconnect AIR pump harness connector. Using test light connected to negative battery terminal, probe AIR pump harness connector terminal "B". Turn ignition on, with engine off. Using scan tool, enable AIR pump. If test light illuminates, go to next step. If test light does not illuminate, go to step 24).
  7. Turn ignition off. Reconnect AIR pump harness connector. Disconnect AIR pump outlet hose. Turn ignition on. Using scan tool, enable AIR pump. If air is present at pump outlet, go to next step. If air is not present, go to step 31).
  8. Check for restriction or blockage in AIR hoses/pipes between AIR pump and to where system branches to both sides of engine. Repair as necessary. After repairs, go to step 35). If AIR hoses/pipes are not restricted or blocked, go to next step.
  9. Remove vacuum bleed valve line from "T" fitting in AIR pump outlet hose. Connect a hand-held vacuum pump to this line and apply about 5 in. Hg. If vacuum holds, go to next step. If vacuum does not hold, go to step 13).
  10. Using scan tool, enable AIR pump. If vacuum bleeds off, see DIAGNOSTIC AIDS. If vacuum does not bleed off, go to next step.
  11. Turn ignition off. Disconnect vacuum bleed valve electrical connector. Connect test light between bleed valve harness terminals. Turn ignition on, with engine off. Using scan tool, command AIR pump on and off. If test light illuminates, go to step 33). If test light does not illuminate, go to next step.
  12. With test light connected to ground, probe power feed circuit in vacuum bleed valve harness connector. Using scan tool, command AIR pump on and off. If test light illuminates, go to step 26). If test light does not illuminate, go to step 25).
  13. Check vacuum hose to valve for cranks, splits or other damage. Repair as necessary. After repairs, go to step 35). If vacuum hose is okay, go to step 33).
  14. Repair battery supply circuit to relay. After repairs, go to step 35).
  15. Check fuse to battery feed circuit to relay. If fuse is okay, go to next step. If fuse is open, go to step 17).
  16. Using test light, check power to fuse. If test light illuminates, go to step 27). If test light does not illuminate, go to step 28).
  17. Connect test light to battery voltage and probe relay battery feed circuit in relay connector. If test light illuminates, go to step 29). If test light does not illuminate, go to next step.
  18. Replace fuse. Disconnect AIR pump and vacuum bleed solenoid harness connectors. Connect test light to battery voltage and probe power feed circuit in vacuum bleed solenoid harness connector. If test light illuminates, go to step 30). If test light does not illuminate, go to next step.
  19. Using a test light connected to ground, probe power feed circuit in vacuum bleed solenoid harness connector. Using scan tool, enable AIR pump. If test light illuminates, go to next step. If test light does not illuminate, go to step 32).
  20. Reconnect AIR pump harness connector. Using scan tool, enable AIR pump. Check fuse. If fuse blew again, go to step 34). If fuse is okay, go to next step.
  21. Reconnect vacuum bleed solenoid harness connector. Using scan tool, enable AIR pump. Check fuse. If fuse blew, go to step 33).
  22. Repair open in circuit between AIR pump and relay. After repairs, go to step 35).
  23. Repair faulty ground connection or open AIR pump ground circuit. After repairs, go to step 35).
  24. Repair open in circuit from terminal "B" of AIR pump to splice. After repairs, go to step 35).
  25. Repair open in vacuum bleed solenoid power circuit between solenoid harness connector and splice. After repairs, go to step 35).
  26. Repair open in vacuum bleed solenoid ground circuit. After repairs, go to step 35).
  27. Repair open in circuit between fuse and relay. After repairs, go to step 35).
  28. Repair power feed circuit to fuse. After repairs, go to step 35).
  29. Repair short to ground between fuse and relay. After repairs, go to step 35).
  30. Repair short to ground between relay and AIR pump/vacuum bleed solenoid. After repairs, go to step 35).
  31. Check AIR electrical connections. Repairs as necessary. After repairs, go to step 35). If connections are okay, go to step 35).
  32. Replace AIR pump relay. After repairs, go to step 35).
  33. Replace vacuum bleed solenoid. After repairs, go to step 35).
  34. Replace AIR pump. After repairs, go to next step.
  35. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0410. 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).
  36. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

AIR vacuum bleed system contains a one-way check valve. If system checks out okay, ensure valve is not stuck closed, restricted or blocked. check valve is located in-line with hose going to vacuum bleed valve.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command AIR solenoid relay on and off. If relay turns on and off as commanded, go to next step. If relay does not turn on or off when commanded, go to step 5).
  3. Turn ignition off. Disconnect PCM harness connector containing relay control circuit. Turn ignition on. Install DVOM. Set DVOM to 10-amp scale. Check current from relay control circuit in PCM harness connector to ground for 2 minutes. If current draw is less than .75 amp (but not zero), see DIAGNOSTIC AIDS. If current draw is not as specified, go to next step.
  4. Turn ignition off. Remove AIR solenoid relay. Check resistance from relay control circuit in PCM harness connector to ground. If resistance is infinite, go to step 12). If resistance is not infinite, go to step 10).
  5. Turn ignition off. Remove AIR solenoid relay. Connect test light between relay coil terminals in relay harness connector. Turn ignition on. Using scan tool, command 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.
  6. Connect test light to ground and probe ignition feed circuit in AIR solenoid relay harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
  7. Turn ignition off. Reinstall AIR solenoid relay. Disconnect PCM harness connector containing relay control circuit. Turn ignition on. Connect a fused jumper wire between to ground and PCM connector (harness side), relay control circuit. If relay operates, go to step 9). If relay does not operate, go to step 10).
  8. Check connections at AIR solenoid relay. Repair as necessary. After repairs, go to step 14). If relay connection is okay, go to step 12).
  9. Check connections at PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 13).
  10. Repair faulty AIR solenoid relay control circuit. After repairs, go to step 14).
  11. Repair faulty AIR solenoid relay ignition feed circuit. After repairs, go to step 14).
  12. Replace AIR solenoid relay. After replacing relay, 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 DTC P0412. 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).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORD 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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. If any other DTC(s) are present, diagnose affected DTC(s) first. If other DTC(s) are not present, go to next step.
  3. Check that 3-way catalytic converter is original equipment. Check for converter damage and rattle inside converter. Inspect for exhaust system leak, especially near HO2S. Ensure HO2S connectors are secured and not touching exhaust. If damage to converter is obvious, go to next step. Repair other exhaust leaks. After repairs, go to step 5).
  4. Replace catalytic converter. After replacing converter, go to next step.
  5. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0420. 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).
  6. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. If any other DTC(s) are present, diagnose affected DTC(s) first. If other DTC(s) are not present, go to next step.
  3. Check that 3-way catalytic converter is original equipment. Check for converter damage and rattle inside converter. Inspect for exhaust system leak, especially near HO2S. Ensure HO2S connectors are secured and not touching exhaust. If damage to converter is obvious, go to next step. Repair other exhaust leaks. After repairs, go to step 5).
  4. Replace catalytic converter. After replacing converter, go to next step.
  5. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0430. 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).
  6. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. If DTC P0443 is present, diagnose DTC P0443 first. Turn ignition on, with engine off. Using scan tool, check EVAP vacuum switch status. If scan tool indicates that EVAP vacuum switch is not purging, go to next step. If scan tool indicates that EVAP vacuum switch is purging, go to step 5).
  3. Start engine. Using scan tool, command EVAP canister purge solenoid on, while observing EVAP vacuum switch status. If scan tool indicates that canister is purging when solenoid is commanded on, see DIAGNOSTIC AIDS. If solenoid is not purging when commanded on, go to next step.
  4. Turn ignition off. Disconnect purge hose from EVAP vacuum switch. Connect a vacuum gauge to canister side of EVAP switch. Start engine. Using scan tool, command EVAP canister purge solenoid on, while observing vacuum gauge. If vacuum gauge indicates vacuum reading close to engine vacuum when solenoid is commanded on, go to next step. If vacuum reading is close to engine vacuum, go to step 7).
  5. Disconnect EVAP vacuum switch harness connector. If scan tool indicates PURGE, go to step 9). If scan tool does not indicate PURGE, go to next step.
  6. Turn ignition off. Disconnect PCM connector. Using DVOM, check continuity between EVAP vacuum switch signal circuit and ground. If DVOM reads infinity, go to step 10). If DVOM does not read infinity, go to step 12.
  7. Disconnect vacuum harness from EVAP canister purge solenoid and connect vacuum gauge to manifold side of vacuum harness. If normal manifold vacuum is indicated, go to next step. If manifold vacuum is not indicated, go to step 13).
  8. Rotate vacuum harness connector enough to reconnect only manifold vacuum supply hose to solenoid. Connect vacuum gauge to other port on solenoid. Using scan tool, command EVAP canister purge solenoid on, while observing vacuum gauge. If vacuum is indicated when solenoid is commanded on, go to step 14). If vacuum is not indicated when solenoid is commanded on, go to step 15).
  9. Replace EVAP vacuum switch. After replacing vacuum switch, go to step 16).
  10. Check connections at PCM. After repairs, go to step 16).
  11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 16).
  12. Repair signal circuit shorted to ground. After repairs, go to step 16).
  13. Check for blocked or restricted manifold vacuum port. Check for kinked or leaking hose between EVAP solenoid and intake manifold. Repair as necessary. After repairs, go to step 16). If vacuum port and vacuum lines to affected components are okay, go to next step.
  14. Check for restricted, kinked or leaking hose between EVAP solenoid and vacuum switch. After repairs, go to step 16).
  15. Replace EVAP solenoid. After replacing solenoid, 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 DTC P0441. 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).
  17. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Before replacing any components, check for misrouted harness, rubbed-through wire insulation, wire broken inside insulation, kinked or damaged vacuum hoses or for physical damage to system components.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command EVAP solenoid on and off. If solenoid turns on and off as commanded, go to next step. If solenoid does not turn on or off when commanded, go to step 5).
  3. Turn ignition off. Disconnect PCM harness connector containing solenoid control circuit. Turn ignition on. Using DVOM, set DVOM to 10-amp scale. Check current from solenoid control circuit in PCM harness connector to ground for 2 minutes. If current draw is less than .75 amp. (but not zero), see DIAGNOSTIC AIDS. If not, go to next step.
  4. Turn ignition off. Disconnect EVAP solenoid. Using DVOM, check resistance from solenoid control circuit in PCM harness connector and ground. If resistance is not infinite, go to step 12). If resistance is infinite, go to step 10).
  5. Turn ignition off. Disconnect EVAP solenoid. Connect test light between solenoid harness connectors. Turn ignition on. Using scan tool, command 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.
  6. Connect test light ground and probe ignition feed circuit in solenoid harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
  7. Turn ignition off. Reconnect EVAP solenoid. Disconnect PCM connector containing solenoid control circuit. Turn ignition on. Connect a fused jumper wire between ground and PCM connector (harness side), solenoid control circuit. If solenoid operates, go to step 9). If solenoid does not operate, go to step 10).
  8. Check connections at EVAP solenoid. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 12).
  9. Check connections at PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 13).
  10. Repair faulty EVAP solenoid control circuit. After repairs, go to step 14).
  11. Repair faulty EVAP solenoid ignition feed circuit. After repairs, go to step 14).
  12. Replace EVAP solenoid. After replacing solenoid, go to step 14).
  13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, 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 DTC P0443. 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).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. CAUTION: On vehicles with independent suspension, support lower control arms so drive axles are in normal horizontal position or drive axles will be damaged.
  2. Turn ignition off. Raise and support drive axles. Disable ASR/TCS system (if equipped). Start engine. With engine at idle, place transmission in gear. Using scan tool, monitor vehicle speed. If displayed vehicle speed is more than zero, see DIAGNOSTIC AIDS. If displayed vehicle speed is zero MPH, go to next step.
  3. Turn ignition off. Disconnect VSS harness connector. Connect Signal Generator Tester (J 33431-B) to VSS harness. Turn ignition on. Set tester to generate VSS signal. Using scan tool, monitor displayed vehicle speed. If displayed vehicle speed is more than zero MPH, go to next step. If displayed vehicle speed is zero MPH, go to 5).
  4. Replace faulty VSS harness connector or faulty VSS. After repairs, go to step 12).
  5. Using DVOM, check voltage between VSS signal circuit to chassis ground. If voltage reading is about 5 volts, go to next step. If not, go to step 9).
  6. Using DVOM, check voltage between VSS signal circuit to VSS ground circuit. If voltage reading is about 5 volts, go to next step. If not, go to step 10).
  7. Check vehicle calibration code. If calibration is correct, go to next step. If calibration is incorrect, go to step 11).
  8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 12).
  9. Repair signal circuit to VSS. After repairs, go to step 12).
  10. Repair ground circuit to VSS. After repairs, go to step 12).
  11. Install proper or most current calibration code. After entering calibration code, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0500. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If all circuits to PCM and VSS have been thoroughly checked, check terminal connections at VSS harness connector and at PCM harness connector. If terminals and connectors are okay, replace PCM.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start engine. Using scan tool, command RPM from about 500 to 1500 RPM. Repeat 2 times and exit from test. If RPM change responded to within 50 RPM of each command, see DIAGNOSTIC AIDS. If RPM does not respond as commanded, go to next step.
  3. If engine RPM is too high (more than 50 RPM of desired RPM), go to next step. If RPM does not change significantly, go to step 5).
  4. Check for vacuum leaks, throttle plates not closing properly or for faulty PCV valve. Repair as necessary. After repairs, go to step 6).
  5. Check for excessive deposits in throttle Body. Check for parasitic load on engine (i.e. transmission problem). Repair as necessary. After repairs, go to next step.
  6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0506. 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).
  7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start engine. Using scan tool, command RPM from about 500 to 1500 RPM. Repeat 2 times and exit from test. If RPM change responded to within 50 RPM of each command, see DIAGNOSTIC AIDS. If RPM does not respond as commanded, go to next step.
  3. If engine RPM is too high (more than 50 RPM of desired RPM), go to next step. If RPM does not change significantly, go to step 5).
  4. Check for vacuum leaks, throttle plates not closing properly or for faulty PCV valve. Repair as necessary. After repairs, go to step 6).
  5. Check for excessive deposits in throttle Body. Check for parasitic load on engine (i.e. transmission problem). Repair as necessary. After repairs, go to next step.
  6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0507. 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).
  7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. Go to step 3).
  2. Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P1635. If DTC P1635 failed this ignition cycle, diagnose DTC. If DTC does not fail this ignition, go to next step.
  3. Turn ignition on, with engine on. Using scan tool, monitor A/C high side. If A/C high side voltage is 0.1-1.8 volts, go to next step. If not, go to step 5).
  4. Turn ignition on, with engine off. Review FREEZE FRAME data and note parameters. Operate vehicle within FREEZE FRAME parameters. If test indicates that this test failed this ignition cycle while operating vehicle, go to next step. If test does not indicate that this test failed this ignition cycle, see DIAGNOSTIC AIDS.
  5. Disconnect A/C refrigerant pressure sensor harness connector. If A/C high side voltage is less than one volt, go to next step. If voltage is more than one volt, go to step 10).
  6. Using DVOM, check voltage between A/C refrigerant pressure sensor 5-volt reference circuit and battery ground. If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step 11).
  7. Using DVOM, check voltage between A/C refrigerant pressure sensor 5-volt reference circuit and sensor ground. If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step 12).
  8. Connect a fused jumper wire between A/C refrigerant pressure sensor 5-volt reference circuit to sensor signal ground. DVOM should read about 5 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 13).
  9. Repair faulty A/C refrigerant pressure sensor connection or replace faulty sensor. After repairs, go to step 14).
  10. Repair A/C refrigerant pressure sensor signal circuit shorted to voltage. After repairs, go to step 14).
  11. Repair 5-volt reference circuit to pressure sensor. After repairs, go to step 14).
  12. Repair ground circuit to pressure sensor. After repairs, go to step 14).
  13. Repair signal circuit to pressure sensor. After repairs, 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 DTC P0530. 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 3).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If test failed on this ignition cycle, wiggle related electrical harness connectors while monitoring scan tool.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If DTC(s) P0530, P1545 or P1546 are present, diagnose affected DTC(s) first.
  2. Start and operate engine at idle. Turn A/C on. If A/C clutch engages, go to next step. If A/C clutch does not engage, go to step 5).
  3. Using scan tool, select ENGINE 1 DATA LIST and observe A/C high pressure side. Turn A/C off for 10 seconds. Turn A/C on for 10 seconds. If A/C high side pressure increases to more than 4 psi (.3 kg/cm 2 ) when A/C is turned on, see DIAGNOSTIC AIDS. If A/C high side pressure does not increase to more than 4 psi (.3 kg/cm 2 ) when A/C is turned on, go to next step.
  4. Repair faulty A/C refrigerant pressure sensor connection or for faulty pressure sensor. After repairs, go to step 12).
  5. If scan tool indicates that A/C clutch is on, go to step 7). If scan tool does not indicate that A/C clutch is on, go to next step.
  6. Repair intermittent A/C clutch circuit from A/C relay to splice. After repairs, go to step 12).
  7. Turn ignition off. Disconnect A/C compressor clutch harness connector. Using a test light connected to battery ground, probe A/C clutch battery supply circuit. Start engine and turn A/C on. If test light illuminates, go to next step. If test light does not illuminate, go to step 10).
  8. Using test light, probe A/C compressor clutch battery supply circuit to A/C compressor clutch ground circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
  9. Repair faulty A/C clutch connection or open A/C clutch coil. After repairs, go to step 12).
  10. Repair open or shorted A/C clutch battery supply circuit. After repairs, go to step 12).
  11. Repair open in A/C clutch ground circuit. After repairs, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0531. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Inspect harness going to A/C clutch and PCM for intermittent connections. With engine running and A/C on, wiggle related electrical connectors and harnesses. This may aid in locating and intermittent fault. Scan tool fail records buffer feature may also help locate a fault. Drive vehicle in conditions that are noted from failure data record.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start engine. Turn on headlights and blower fan to high, to load electrical system. Using DVOM, check battery voltage at battery. If battery voltage is less than 8 volts, check/diagnose charging system. If battery voltage is more than 8 volts, go to next step.
  3. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, check voltage at PCM ignition feed terminal. If voltage is less than 8 volts, go to step 7). If voltage is 8 volts or more, go to next step.
  4. Check for faulty connections at PCM. Repair as necessary. After repairs, go to step 8). If connections are okay, go to next step.
  5. Turn ignition off. Reconnect PCM connector. Turn ignition on. Using scan tool, select ENG DTC, DTC INFO unction. If any DTC(s) are displayed, diagnose affected DTC(s) first. If DTC(s) are not present, go to next step.
  6. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 8).
  7. Repair ignition feed circuit to PCM as necessary. After repairs, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0562. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

An extremely low system voltage (less than 7 volts) may cause loss of serial data and MIL may not activate. An open ignition feed circuit will cause a no-start and MIL will not illuminate. Low system voltage may cause DTC to set.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn off all accessories. Start and operate engine at more than 2000 RPM. Using DVOM, check battery voltage at battery. If battery voltage is less than 17.1 volts, see DIAGNOSTIC AIDS. If battery voltage is more than 17.1 volts, go to next step.
  3. Repair charging system. After repairs, go to next step.
  4. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0563. 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).
  5. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Check generator voltage sense circuit for high resistance or loose connections, causing intermittent overcharging condition.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0601. 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).
  4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Replace PCM even if DTC only exists as a history code.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Flash PCM with current software. If DTC is reset, go to next step. If DTC does not reset, go to step 5).
  3. Verify that test equipment used is operating properly and that all connections are clean and tight. Attempt to flash PCM again. If DTC resets, go to next step. If DTC does not reset, go to step 5).
  4. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  5. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0602. 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).
  6. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, select ENGINE 1 DATA LIST and MAP. Monitor scan tool while moving PCM and MAP sensor connectors and harness. If MAP value is affected when moving harness and connectors, go to step 10). If MAP value does not change when moving harness and connectors, go to next step.
  3. Turn ignition on, with engine off. If MAP sensor reading is more than 85 kPa, go to next step. If MAP sensor reading is less than 85 kPa, go to step 11).
  4. Remove MAP sensor from intake manifold, without disconnecting harness connector. Install a hand-held vacuum pump to MAP sensor. Slowly apply up to 20 in. Hg and observe MAP reading on scan tool. Each one inch of vacuum applied should result in a 3-4 kPa drop in MAP value and should change smoothly with each increase in vacuum. If MAP value change smoothly, go to step 11). If MAP value change is erratic, go to next step.
  5. Apply 20 in. Hg to MAP sensor. If MAP sensor reading on scan tool is about 34 kPa, go to next step. If scan tool reading is not as specified, go to step 11).
  6. Remove vacuum source from MAP sensor. If MAP sensor reading returns to original value, go to next step. If MAP sensor reading does not return to original value, go to step 11).
  7. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1107. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  8. Check MAP sensor harness for incorrect routing near secondary ignition or components, solenoids, relays or motors. Correct problem as necessary. After repairs, go to step 14). If harness routing is okay, go to next step.
  9. Check for plugged or leaking vacuum supply to MAP sensor. Repair as necessary. After repairs, go to step 13). If vacuum supply is okay, go to step 12).
  10. Check harness connector terminals for poor connection, improper contact, poor terminals, rubbed-through wire insulation, broken wire inside insulation or misrouted harness. Repair as necessary. After repairs, go to step 14).
  11. Replace MAP sensor. After replacing sensor, go to step 14).
  12. Check connections at PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to next step.
  13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, 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 DTC P1107. 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).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

An intermittent DTC can be caused by Electromagnetic Interference (EMI). Check related circuits for being too close to secondary ignition components and alternator.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition off, with engine off. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P0113. If DTC P0113 failed this ignition cycle, diagnose DTC. If DTC does not fail this ignition, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, observe affected sensor value while moving related harness connectors (at component and PCM). If sensor value changes while moving connectors, go to step 6). If sensor value does not change while moving connectors, go to next step.
  4. Using scan tool, observe affected sensor value while moving related wiring harnesses. If sensor value changes abruptly, go to step 7). If sensor value does not change, go to next step.
  5. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1111. If scan tool indicates that this test failed this ignition, go to step 8). If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  6. Repair damaged connectors or terminals. After repairs, go to step 9).
  7. Repair faulty wiring. After repairs, go to step 9).
  8. Reinspect all related circuits and connectors. If circuits are okay, replace sensor/component. After repairs, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1111. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If other DTC's are present that share same ground and/or 5-volt reference circuit, check for faulty connections or faulty wiring. If engine has been allowed to sit overnight, engine coolant temperature (ECT) and intake air temperature (IAT) sensor values should display within a few degrees of each other. If temperature value is not within 5°F (3°C), see IAT TEMPERATURE-TO-RESISTANCE VALUES table.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition off, with engine off. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P0112. If DTC P0112 failed this ignition cycle, diagnose DTC. If DTC does not fail this ignition, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, observe affected sensor value while moving related harness connectors (at component and PCM). If sensor value changes while moving connectors, go to step 6). If sensor value does not change while moving connectors, go to next step.
  4. Using scan tool, observe affected sensor value while moving related wiring harnesses. If sensor value changes abruptly, go to step 7). If sensor value does not change, go to next step.
  5. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1112. If scan tool indicates that this test failed this ignition, go to step 8). If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  6. Repair damaged connectors or terminals. After repairs, go to step 9).
  7. Repair faulty wiring. After repairs, go to step 9).
  8. Reinspect all related circuits and connectors. If circuits are okay, replace sensor/component. After repairs, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1112. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If other DTC's are present that share same ground and/or 5-volt reference circuit, check for faulty connections or faulty wiring. If engine has been allowed to sit overnight, engine coolant temperature (ECT) and intake air temperature (IAT) sensor values should display within a few degrees of each other. If temperature value is not within 5°F (3°C), see IAT TEMPERATURE-TO-RESISTANCE VALUES table.

Temperature °F (°C)Ohms
212 (100)177
194 (90)241
158 (70)467
122 (50)973
104 (40)1459
86 (30)2238
68 (20)3520
50 (10)5670

IAT TEMPERATURE-TO-RESISTANCE VALUES

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition off, with engine off. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P0118. If DTC P0118 failed this ignition cycle, diagnose DTC. If DTC does not fail this ignition, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, observe affected sensor value while moving related harness connectors (at component and PCM). If sensor value changes while moving connectors, go to step 6). If sensor value does not change while moving connectors, go to next step.
  4. Using scan tool, observe affected sensor value while moving related wiring harnesses. If sensor value changes abruptly, go to step 7). If sensor value does not change, go to next step.
  5. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1114. If scan tool indicates that this test failed this ignition, go to step 8). If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  6. Repair damaged connectors or terminals. After repairs, go to step 9).
  7. Repair faulty wiring. After repairs, go to step 9).
  8. Reinspect all related circuits and connectors. If circuits are okay, replace sensor/component. After repairs, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1114. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

And intermittent DTC can be caused by Electromagnetic Interference (EMI). Inspect related circuits for being too close to secondary ignition wires and alternator.

If other DTC's are present that share same ground and/or 5-volt reference circuit, check for faulty connections or faulty wiring.

If engine has been allowed to sit overnight, engine coolant temperature (ECT) and intake air temperature (IAT) sensor values should display within a few degrees of each other. If temperature value is not within 5°F (3°C), check for skewed ECT sensor. See ECT TEMPERATURE-TO-RESISTANCE VALUES .

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition off, with engine off. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P0117. If DTC P0117 failed this ignition cycle, diagnose DTC. If DTC does not fail this ignition, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, observe affected sensor value while moving related harness connectors (at component and PCM). If sensor value changes while moving connectors, go to step 6). If sensor value does not change while moving connectors, go to next step.
  4. Using scan tool, observe affected sensor value while moving related wiring harnesses. If sensor value changes abruptly, go to step 7). If sensor value does not change, go to next step.
  5. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1115. If scan tool indicates that this test failed this ignition, go to step 8). If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  6. Repair damaged connectors or terminals. After repairs, go to step 9).
  7. Repair faulty wiring. After repairs, go to step 9).
  8. Reinspect all related circuits and connectors. If circuits are okay, replace sensor/component. After repairs, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1115. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

And intermittent DTC can be caused by Electromagnetic Interference (EMI). Inspect related circuits for being too close to secondary ignition wires and alternator.

If other DTC's are present that share same ground and/or 5-volt reference circuit, check for faulty connections or faulty wiring.

If engine has been allowed to sit overnight, engine coolant temperature (ECT) and intake air temperature (IAT) sensor values should display within a few degrees of each other. If temperature value is not within 5°F (3°C), check for a skewed ECT sensor. See ECT TEMPERATURE-TO-RESISTANCE VALUES .

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P0123. If scan tool indicates that DTC P0123 failed this ignition cycle, diagnose DTC. If scan tool does not indicate that DTC P0123 failed this ignition, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, observe affected sensor value while moving related harness connectors (at component and PCM). If sensor value changes abruptly while moving related connectors, go to step 6). If sensor value does not change, go to next step.
  4. Using scan tool, observe affected sensor value while moving related wiring harness. If sensor value changes abruptly while moving related harnesses, go to step 7). If sensor value does not change, go to next step.
  5. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1121. If scan tool indicates that this test failed this ignition, go to step 8). If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  6. Repair damaged connectors/terminals. After repairs, go to step 9).
  7. Repair faulty wiring/harness. After repairs, go to step 9).
  8. Reinspect all related circuits and connectors. If all circuits check okay, replace sensor/components. After repairs, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1121. Operate vehicle within conditions that set 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

An intermittent DTC can be caused by Electromagnetic Interference (EMI). Inspect related circuits for being too close to secondary ignition wires and alternator.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P0122. If scan tool indicates that DTC P0122 failed this ignition cycle, diagnose DTC. If scan tool does not indicate that DTC P0122 failed this ignition, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, observe affected sensor value while moving related harness connectors (at component and PCM). If sensor value changes abruptly while moving related connectors, go to step 6). If sensor value does not change, go to next step.
  4. Using scan tool, observe affected sensor value while moving related wiring harness. If sensor value changes abruptly while moving related harnesses, go to step 7). If sensor value does not change, go to next step.
  5. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1122. If scan tool indicates that this test failed this ignition, go to step 8). If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  6. Repair damaged connectors/terminals. After repairs, go to step 9).
  7. Repair faulty wiring/harness. After repairs, go to step 9).
  8. Reinspect all related circuits and connectors. If all circuits check okay, replace sensor/components. After repairs, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1122. Operate vehicle within conditions that set 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, diagnose affected DTC(s).

An intermittent DTC can be caused by Electromagnetic Interference (EMI). Inspect related circuits for being too close to secondary ignition wires and alternator.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If other DTC(s) are present, diagnose affected DTC(s) first.
  2. Start and warm engine to normal operating temperature. Operate until system goes in "closed loop", engine speed at more than 1000 RPM but less than 1700 RPM, and MAF sensor value between 12-28 gm/s. Using scan tool, monitor FAIL THIS IGN under DTC info. If scan tool indicates that DTC P1133 test failed, go to next step. If scan tool does not indicate that this test failed, see DIAGNOSTIC AIDS.
  3. If scan tool indicates that DTC P1153 test failed, go to step 8). If scan tool does not indicate that DTC P1153 test failed, go to next step.
  4. Check exhaust system for leaks. Repair as necessary. After repairs, go to next step. If exhaust leak is not present, repeat step 2).
  5. Ensure that Bank 1 HO2S 1 is securely installed. Check for corrosion on terminals and terminal tension at sensor and PCM. Check for damaged wiring. Repair as necessary. After repairs, go to step 9). If circuits are okay, go to next step.
  6. Disconnect Bank 1 HO2S 1. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S low signal circuit. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage is within a range of 375-525 mV, go to next step. If HO2S voltage is not as specified, go to step 10).
  7. Connect a fused jumper wire between ground and BANK 1, HO2S 1 high and low signal circuits. Using scan tool, monitor voltage. If voltage is less than 200 mV, go to step 12). If voltage is more than 200 mV, go to step 11).
  8. Replace oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After replacing oxygen sensor, go to step 13).
  9. Repair or replace wiring or terminal as necessary. After repairs, go to step 13).
  10. Repair open in sensor low signal circuit or grounded high signal circuit. After repairs, go to step 13).
  11. Repair open in sensor high signal circuit or faulty PCM connectors. After repairs, go to step 13).
  12. Replace Bank 1 HO2S 1. After replacing oxygen sensor, go to next step.
  13. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1133. 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

A malfunction in HO2S heater circuit will set DTC. Check circuit for intermittent open or faulty connectors. Oxygen supply inside HO2S is provided through wires.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If other DTC(s) are present, diagnose affected DTC(s) first.
  2. Start and warm engine to normal operating temperature. Operate until system goes in "closed loop", engine speed at more than 1000 RPM but less than 1700 RPM, and MAF sensor value between 12-28 gm/s. Using scan tool, monitor FAIL THIS IGN under DTC info. If scan tool indicates that DTC P1134 test failed, go to next step. If scan tool does not indicate that this test failed, see DIAGNOSTIC AIDS.
  3. If scan tool indicates that DTC P1153 test failed, go to step 8). If scan tool does not indicate that DTC P1153 test failed, go to next step.
  4. Check exhaust system for leaks. Repair as necessary. After repairs, go to next step. If exhaust leak is not present, repeat step 2).
  5. Ensure that Bank 1 HO2S 1 is securely installed. Check for corrosion on terminals and terminal tension at sensor and PCM. Check for damaged wiring. Repair as necessary. After repairs, go to step 9). If circuits are okay, go to next step.
  6. Disconnect Bank 1 HO2S 1. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S low signal circuit. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage is within a range of 375-525 mV, go to next step. If HO2S voltage is not as specified, go to step 10).
  7. Connect a jumper wire between ground and PCM connector (PCM side), BANK 1 HO2S 1 high and low signal circuits (PCM side). Using scan tool, monitor voltage. If voltage is less than 200 mV, go to step 12). If voltage is not less than 200 mV, go to step 11).
  8. Replace oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After replacing oxygen sensor, go to step 13).
  9. Repair or replace wiring or terminal as necessary. After repairs, go to step 13).
  10. Repair open in sensor low signal circuit or grounded high signal circuit. After repairs, go to step 13).
  11. Repair open in sensor high signal circuit or faulty PCM connectors. After repairs, go to step 13).
  12. Replace Bank 1 HO2S 1. After replacing oxygen sensor, go to next step.
  13. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1134. 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

A malfunction in HO2S heater circuit will set DTC. Check circuit for intermittent open or faulty connectors. Oxygen supply inside HO2S is provided through wires.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 5.7L article. After performing OBD system check, go to next step. NOTE: If other DTC(s) are present, diagnose affected DTC(s) first.
  2. Start and warm engine to normal operating temperature. Operate until system goes in "closed loop", engine speed at more than 1000 RPM but less than 1700 RPM, and MAF sensor value between 12-28 gm/s. Using scan tool, monitor FAIL THIS IGN under DTC info. If scan tool indicates that DTC P1153 test failed, go to next step. If scan tool does not indicate that this test failed, see DIAGNOSTIC AIDS.
  3. If scan tool indicates that DTC P1133 test failed, go to step 8). If scan tool does not indicate that DTC P1133 test failed, go to next step.
  4. Check exhaust system for leaks. Repair as necessary. After repairs, go to next step. If exhaust leak is not present, repeat step 2).
  5. Ensure that Bank 2 HO2S 1 is securely installed. Check for corrosion on terminals and terminal tension at sensor and PCM. Check for damaged wiring. Repair as necessary. After repairs, go to step 9). If circuits are okay, go to next step.
  6. Disconnect Bank 2 HO2S 1. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S low signal circuit. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage is within a range of 375-525 mV, go to next step. If HO2S voltage is not as specified, go to step 10).
  7. Connect a fused jumper wire between ground and Bank 2 HO2S 1 high and low signal circuits. Using scan tool, monitor voltage. If voltage is less than 200 mV, go to step 12). If voltage is not less than 200 mV, go to step 11).
  8. Replace oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After replacing oxygen sensor, go to step 13).
  9. Repair or replace wiring or terminal as necessary. After repairs, go to step 13).
  10. Repair open in sensor low signal circuit or grounded high signal circuit. After repairs, go to step 13).
  11. Repair open in sensor high signal circuit or faulty PCM connectors. After repairs, go to step 13).
  12. Replace Bank 2 HO2S 1. After replacing oxygen sensor, go to next step.
  13. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1153. 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

A malfunction in HO2S heater circuit will set DTC. Check circuit for intermittent open or faulty connectors. Oxygen supply inside HO2S is provided through wires.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If other DTC(s) are present, diagnose affected DTC(s) first.
  2. Start and warm engine to normal operating temperature. Operate until system goes in "closed loop", engine speed at more than 1000 RPM but less than 1700 RPM, and MAF sensor value between 12-28 gm/s. Using scan tool, monitor FAIL THIS IGN under DTC info. If scan tool indicates that DTC P1134 test failed, go to next step. If scan tool does not indicate that this test failed, see DIAGNOSTIC AIDS.
  3. If scan tool indicates that DTC P1134 test failed, go to step 8). If scan tool does not indicate that DTC P1134 test failed, go to next step.
  4. Check exhaust system for leaks. Repair as necessary. After repairs, go to next step. If exhaust leak is not present, repeat step 2).
  5. Ensure that Bank 2 HO2S 1 is securely installed. Check for corrosion on terminals and terminal tension at sensor and PCM. Check for damaged wiring. Repair as necessary. After repairs, go to step 9). If circuits are okay, go to next step.
  6. Disconnect Bank 2 HO2S 1. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S low signal circuit. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage is within a range of 375-525 mV, go to next step. If HO2S voltage is not as specified, go to step 10).
  7. Connect a fused jumper wire between ground and PCM connector (PCM side), BANK 2 HO2S 1 high and low signal circuits. Using scan tool, monitor voltage. If voltage is less than 200 mV, go to step 12). If voltage is more than 200 mV, go to step 11).
  8. Replace oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After replacing oxygen sensor, go to step 13).
  9. Repair or replace wiring or terminal as necessary. After repairs, go to step 13).
  10. Repair open in sensor low signal circuit or grounded high signal circuit. After repairs, go to step 13).
  11. Repair open in sensor high signal circuit or faulty PCM connectors. After repairs, go to step 13).
  12. Replace Bank 1 HO2S 1. After replacing oxygen sensor, go to next step.
  13. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1154. 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).
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

A malfunction in HO2S heater circuit will set DTC. Check circuit for intermittent open or faulty connectors. Oxygen supply inside HO2S is provided through wires.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

PCM can identify if vehicle fuel system is capable of supplying adequate amount of fuel during heavy acceleration (power enrichment). When power enrichment mode of operation is requested during "closed loop" operation, PCM will provide more fuel to engine. Under these conditions, PCM should detect a rich condition.

DTC will set when following conditions are present

  1. DTCs P0131, P0132, P0133, P0134, P0135, P0153, P0154, P0155, P0157, P0158, P0160, P0161, P0410, P0412, P1112, P1114, P1121, P1153 or P1155 not set.
  2. Engine operating in closed loop.
  3. Not in fuel cutoff mode.
  4. PCM detects lean oxygen sensor voltage for 3 seconds during power enrichment mode.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: If any HO2S related DTC is present, diagnose affected code first.
  2. Turn ignition off. Install fuel pressure gauge. Turn ignition on, with engine off. Fuel pump should operate for about 2 seconds. It may be necessary to cycle ignition on more than once to obtain maximum fuel pressure reading. Note fuel pressure with fuel pump running. Fuel pressure should be 41-47 psi (2.9-3.3 kg/cm 2 ) and hold steady. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, diagnose fuel system. See the SYSTEM/COMPONENT TESTS article.
  3. Check for restricted fuel filter, restricted or damaged fuel line, restricted/clogged fuel pump strainer. Repair as necessary. After repairs, go to step 5). If components are okay, go to next step.
  4. Replace fuel pump. After replacing fuel pump, go to next step.
  5. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1171. 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).
  6. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

A restricted fuel filter can supply adequate fuel at idle but not enough during heavy acceleration. A vapor lock condition can also set DTC. If DTC cannot be reset, original cause of DTC could have been caused by engine running out of fuel.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and idle engine. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P0200. If scan tool indicates that DTC P0200 failed this ignition, diagnose affected DTC. If scan tool does not indicate that DTC P0200 failed this ignition, go to next step.
  3. Using scan tool, select MISFIRE DATA LIST and monitor MISFIRE HIST. COUNTERS. If counter indicates a number other than 0.0 counts, go to step 5). If counter does not indicate 0.0 counts, go to next step.
  4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1222. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  5. Using scan tool, select MISFIRE DATA LIST and monitor MISFIRE HIST. COUNTERS for affected cylinder, while moving related harness connectors (at injector and PCM). If counter value starts incrementing, go to next step. If counter value does not change, diagnose fuel injector. See the SYSTEM/COMPONENT TESTS article.
  6. Turn ignition off. Disconnect harness connector to affected injectors. Turn ignition on. Using a test light connected to ground, probe injector harness connector ignition feed circuit. If test light illuminates, go to step 9). If test light does not illuminate, go to next step.
  7. Turn ignition off. Disconnect PCM connector. Connect a fused jumper wire between ground and PCM connector (harness side), injector control circuit for affected cylinder. Connect test light to battery positive. Probe injector feed circuits of one of disconnected injector harnesses. If test light illuminates, go to next step. If test light does not illuminate, go to step 10).
  8. Repair injector driver circuit to affected injector. After repairs, go to step 11).
  9. Repair injector driver feed circuit. After repairs, go to step 11).
  10. Reinspect all related circuit and connections. Repair as necessary. After repairs, go to next step. If circuits and connections are okay, diagnose fuel injection. See the SYSTEM/COMPONENT TESTS article.
  11. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1222. 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).
  12. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If an injector is disconnected while engine is operating and if DTC P0200 is present, injector driver will be disabled for entire ignition cycle. When injector driver is disabled, engine misfire will be apparent and a misfire related DTC will set.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Attempt to start engine. If engine starts, see DIAGNOSTIC AIDS. If engine does not start, go to next step.
  3. Turn ignition off. Disconnect IC module harness connector. Using DVOM, set DVOM to 40-volt range and peak min/max adjustment. Check voltage between IC module harness connector terminal "B" and ground while cranking engine. If voltage is about 1.0-4.0 volts, go to next step. If voltage is not as specified, go to step 5).
  4. Turn ignition on, with engine off. Connect test light to battery voltage and probe IC module harness connector terminal "C". If test light illuminates, go to step 7). If test light does not illuminate, go to step 6).
  5. Repair IC circuit. After repairs, go to step 8).
  6. Repair open in IC module ground circuit. After repairs, go to step 8).
  7. Replace faulty IC module. After replacing module, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1351. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Attempt to start engine. If engine starts, see DIAGNOSTIC AIDS. If engine does not start, go to next step.
  3. Turn ignition off. Disconnect IC module harness connector. Using DVOM, set DVOM to 40-volt range and peak min/max adjustment. Check voltage between IC module harness connector terminal "B" and ground while cranking engine. If voltage is within a range of 1.0-4.0 volts, go to next step. If voltage is not as specified, go to step 5).
  4. Turn ignition on, with engine off. Connect test light to battery voltage and probe IC module harness connector terminal "C". If test light illuminates, go to step 7). If test light does not illuminate, go to step 6).
  5. Repair IC circuit. After repairs, go to step 8).
  6. Repair open in IC module ground circuit. After repairs, go to step 8).
  7. Replace faulty IC module. After replacing module, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1361. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Using scan tool, monitor engine speed. Crank engine. If scan tool indicates RPM while cranking, go to next step. If scan tool does not indicate RPM while cranking, go to step 4).
  3. Start engine. With engine running, move related harnesses and connectors between distributor and PCM. If engine cuts out or misses, go to next step. If engine does not cut out or miss, see DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect ignition system test connector. Turn ignition on. Using DVOM, check voltage on terminal "A" at PCM side of ignition test connector. If voltage reading is 5 volts, go to next step. If not, go to step 8).
  5. Turn ignition off. Reconnect ignition test connector. Disconnect distributor connector. Turn ignition on. Using DVOM, check voltage on terminal "A" of distributor harness connector. If voltage is 5 volts, go to step 11). If voltage is not as specified, go to step 6).
  6. If voltage is more than 5 volts, go to next step. If voltage is less than 5 volts, go to step 12).
  7. Repair short to voltage on low resolution signal circuit from PCM to ignition test connector. After repairs, go to step 15).
  8. If voltage is more than 5 volts, go to step 10). If voltage is less than 5 volts, go to next step.
  9. Repair open or grounded low resolution circuit from ignition test connector to PCM. After repairs, go to step 15). If circuit is okay and repairs are not necessary, go to step 14).
  10. Repair short to voltage on low resolution signal circuit from ignition test connector to distributor. After repairs, go to step 15).
  11. Repair faulty distributor connection or faulty distributor. After repairs, go to step 15).
  12. Repair open or grounded low resolution circuit from ignition test connector to distributor. After repairs, go to step 15). If circuit is okay and repairs are not necessary, go to step 14).
  13. Repair harness or connections as necessary. After repairs, go to step 15).
  14. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  15. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1371. 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).
  16. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Use of Connector Test Adapter Kit (J 35616-A) is required when probing PCM or component harness connectors to prevent terminal damage.

DTC P1371 will set if high and low resolution circuits are shorted together. Inspect circuit before replacing component.

When an intermittent DTC P1371 occurs, a misfire will be apparent. To locate intermittent, use scan tool's snapshot feature. Try to duplicate conditions under which misfire is present. When reviewing captured data, watch for any abnormal high and low resolution timing pulses.

If DTC P1351 and/or P1361 is also set with P1371 and no external fault can be found, replace PCM. If only DTC P1371 is set and distributor connectors are okay, replace distributor. If distributor components must be replaced, check distributor vent system operation.

If DTC is not present and a no-start condition is exists, see ENGINE CRANKS, BUT DOES NOT START diagnosis in the BASIC TESTING - 5.7L article.

PCM detects engine misfire by detecting variations in crankshaft deceleration between firing strokes. For accurate detection of engine misfire, PCM must be able to distinguish between crankshaft deceleration caused by actual misfire or deceleration caused by rough road conditions.

ABS system can detect if vehicle is on a rough road based on wheel acceleration/deceleration data supplied by wheel speed sensors. If ABS system detects rough road above a predetermined threshold, this information is sent to PCM via serial data. PCM can then take rough road into account when calculating misfire. Even if ABS is malfunctioning and cannot detect rough roads, misfire diagnostic will continue to run. However, if a misfire DTC is set, this additional DTC will also set indicating that rough road data was not available during misfire calculation due to ABS system malfunction.

DTC will set when following conditions are present

  1. DTCs P0100, P0101, P0102, P0103, P0122, P0123, P0335, P0336, P0742, P1120, P1121, P1220 or P1221 not set.
  2. Vehicle speed more than 5 MPH.
  3. Light to moderate engine load.
  4. DTC P0300 set.
  5. An ABS system malfunction exists preventing rough road detection data.

Note. ABS system must be diagnosed/serviced before diagnosing misfire. Actual engine misfire may or may not exist.

Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 5.7L article. After performing OBD system check, perform ABS system diagnosis. See the BRAKES SYSTEM - ANTI-LOCK article in the BRAKES section.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles occurred since diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

PCM detects engine misfire by detecting variations in crankshaft deceleration between firing strokes. For accurate detection of engine misfire, PCM must be able to distinguish between crankshaft deceleration caused by actual misfire or deceleration caused by rough road conditions.

ABS system can detect if vehicle is on a rough road based on wheel acceleration/deceleration data supplied by wheel speed sensors. If ABS system detects rough road above a predetermined threshold, this information is sent to PCM via serial data. PCM can then take rough road into account when calculating misfire. Even if ABS is malfunctioning and cannot detect rough roads, misfire diagnostic will continue to run. However, if a misfire DTC is set, this additional DTC will also set indicating that rough road data was not available during misfire calculation due to ABS system malfunction.

DTC will set when following conditions are present

  1. Vehicle speed more than 10 MPH.
  2. Engine speed less than 3500 RPM.
  3. Light to moderate engine load.
  4. DTC P0300 set.
  5. A serial data malfunction exists preventing rough road detection data.
  6. Conditions met for 20 seconds.

Note. Serial data must be serviced before diagnosing misfire. Actual engine misfire may or may not exist.

Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 5.7L article. After performing OBD system check, perform ABS system diagnosis. See the BRAKES SYSTEM - ANTI-LOCK article in the BRAKES section.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

Test I

  1. When AIR pump is enabled, PCM monitors HO2S voltage. If HO2S voltages drop below a threshold, PCM interprets this as an indication that pump is operational.
  2. When AIR pump is disabled, PCM monitors HO2S voltages. HO2S voltages should increase above a threshold and switch normally. If PCM does not sense more than a predetermined amount of HO2S rich switches, a malfunction will be reported.

Test II

  1. During this test, PCM will activate AIR pump during "closed loop" operation. When AIR is activated, PCM will monitor HO2S voltages and short term fuel trim values for both engine banks. If AIR is operating properly, HO2S voltages should go low and short term fuel trim should go high.
  2. PCM checks that HO2S voltages return to a rich threshold when pump is disabled. If PCM determines that HO2S voltages for both banks does not respond as expected during test, DTC P0410 will set. If only one sensor responded, PCM will set either a DTC P1415 or P1416 to indicate on which bank AIR system is inoperative. DTC will set when following conditions are present: DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0133, P0135, P0152, P0155, P0171, P0172, P0174, P0175, P0300, P0412, P0418, P0441, P0443, P1120, P1220, P1221, P1441 no HO2S DTCs set. Engine operating 2 seconds.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and operate engine to "closed loop" status. Turn off all accessories. Using scan tool, select ENGINE 1 DATA LIST and monitor Bank 1 HO2S 1 (left front) voltage display. If HO2S voltage drops to less than 350 mV, see DIAGNOSTIC AIDS. If HO2S voltage does not drop to less than 350 mV, go to next step.
  3. Ensure all hoses and pipes are connected and clamps secure. Check for heat damaged components. Repair as necessary. After repairs, go to step 6). If components are okay, go to next step.
  4. Disconnect hose from check valve at left exhaust manifold. Using scan tool, enable AIR pump. If air is present at hose outlet, go to step 7). If air is not present, go to next step.
  5. Repair restriction or blockage in AIR hoses/pipes between left exhaust manifold and where system branches to both sides of engine. After repairs, go to step 8).
  6. Repair as necessary. After repairs, go to step 8).
  7. Replace check valve. After replacing check valve, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1415. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Casting flash in exhaust manifold may restrict amount of airflow necessary to affect HO2S voltage. Remove air pipe from manifold and inspect passage.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. When AIR pump is enabled, PCM monitors HO2S voltage. If HO2S voltages go below a threshold, PCM interprets this as an indication that pump is operational.
  2. When AIR pump is disabled, PCM monitors HO2S voltages. HO2S voltages should increase above a threshold and switch normally. If PCM does not sense more than a predetermined amount of HO2S rich switches, a malfunction will be reported.
  1. During this test, PCM will activate AIR pump during "closed loop" operation. When AIR is activated, PCM will monitor HO2S voltages and short term fuel trim values for both engine banks. If AIR is operating properly, HO2S voltages should go low and short term fuel trim should go high.
  2. PCM checks that HO2S voltages return to a rich threshold when pump is disabled. If PCM determines that HO2S voltages for both banks does not respond as expected during tests, DTC P0410 will set. If only one sensor responded, PCM will set either DTC P1415 or P1416 to indicate which bank AIR system is inoperative. DTC will set when following conditions are present: DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0133, P0135, P0152, P0155, P0171, P0172, P0174, P0175, P0300, P0412, P0418, P0441, P0443, P1120, P1220, P1221, P1441 no HO2S DTCs set. Engine operating 2 seconds.
  1. Perform Powertrain On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Start and operate engine to "closed loop" status. Turn off all accessories. Using scan tool, select ENGINE 1 DATA LIST and monitor Bank 2 HO2S 1 (right front) voltage display. If HO2S voltage drops to less than 350 mV, see DIAGNOSTIC AIDS. If HO2S voltage does not drop to less than 350 mV, go to next step.
  3. Ensure all hoses and pipes are connected and clamps secure. Check for heat damaged components. Repair as necessary. After repairs, go to step 6). If components are okay, go to next step.
  4. Disconnect hose from check valve at right exhaust manifold. Using scan tool, enable AIR pump. If air is present at hose outlet, go to step 7). If air is not present, go to next step.
  5. Repair restriction or blockage in AIR hoses/pipes between left exhaust manifold and where system branches to both sides of engine. After repairs, go to step 8).
  6. Repair as necessary. After repairs, go to step 8).
  7. Replace check valve. After replacing check valve, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1416. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Casting flash in exhaust manifold may restrict amount of air flow necessary to affect HO2S voltage. Remove air pipe from manifold and inspect passage.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step. NOTE: DTC will set if vacuum lines at EVAP purge solenoid are reversed.
  2. Turn ignition on, with engine off. Using scan tool, check EVAP vacuum switch status. If scan tool indicates that EVAP vacuum switch is not purging, go to next step. If scan tool indicates that EVAP vacuum switch is purging, go to step 6).
  3. Start engine. Using scan tool, check EVAP vacuum switch status. If EVAP vacuum switch status changes to PURGE when engine is started, go to step 19). If EVAP vacuum switch status does not change to PURGE when engine is started, go to next step.
  4. Start engine and increase engine speed to 1500 RPM. Using scan tool, command EVAP canister purge solenoid on and off, while observing EVAP vacuum switch status. If scan tool indicates NO PURGE within 5 seconds, see DIAGNOSTIC AIDS. If scan tool does not indicate NO PURGE within 5 seconds, go to next step.
  5. Turn ignition off. Disconnect purge hose from EVAP vacuum switch. Start engine and increase engine speed to 1500 RPM. Using scan tool, command EVAP canister purge solenoid on and off, while EVAP vacuum switch status. If scan tool indicates NO PURGE within 5 seconds, go to step 11). If scan tool does not indicate NO PURGE within 5 seconds, go to step 12).
  6. Disconnect EVAP vacuum switch harness connector. Using test light connected to battery voltage, probe ground circuit at EVAP vacuum switch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
  7. Connect a fused jumper wire across EVAP vacuum switch harness connector terminals. If scan tool indicates EVAP vacuum switch NO PURGE, go to step 14). If EVAP vacuum switch does not indicate NO PURGE, go to next step.
  8. Using DVOM, check voltage at signal circuit of EVAP vacuum switch harness connector and ground. Battery voltage should be present. If battery voltage is present, go to step 18). If battery voltage is not present, go to next step.
  9. Turn ignition off. Disconnect PCM connector C2. Using DVOM, check continuity between EVAP vacuum switch signal circuit and ground. If DVOM does not read infinity, go to step 16).
  10. Using DVOM, check continuity of EVAP vacuum switch signal circuit from vacuum switch harness connector to PCM connector. If resistance is less than 5 ohms, go to step 20). If resistance is more than 5 ohms, go to step 17).
  11. Replace EVAP canister. After replacing canister, go to step 21).
  12. Repair restricted or kinked hose between canister and EVAP vacuum switch. After repairs, go to step 21).
  13. Repair open ground circuit. After repairs, go to step 21).
  14. Check connections at EVAP vacuum switch. Repair as necessary. After repairs, go to step 21). If connections are okay, go to next step.
  15. Replace EVAP switch. After replacing switch, go to step 21).
  16. Repair shorted signal to ground. After repairs, go to step 21).
  17. Repair open signal circuit. After repairs, go to step 21).
  18. Check connections at PCM. Repair as necessary. After repairs, go to step 21). If connections are okay, go to step 20).
  19. Replace EVAP canister purge solenoid. After replacing solenoid, go to step 21).
  20. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 16).
  21. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1441. 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).
  22. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Before replacing any components, check for misrouted harness, rubbed-through wire insulation, wire broken inside insulation, kinked or damaged vacuum hoses or for physical damage to system components.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start engine. Using scan tool, command RPM from 500 to 1500 RPM. Repeat 2 times and exit from test. If RPM change responded to within 50 RPM with each command, see DIAGNOSTIC AIDS. If RPM does not respond as commanded, go to next step.
  3. Turn ignition off. Disconnect IAC harness connector and install IAC Node Light (J 37027-A). Start engine. Using scan tool, command RPM up to 1500 down to 500 and up to 1500 RPM, while observing node light. If node light Red and Green LEDs cycle, but are never off, go to next step. If not, go to step 5).
  4. Turn ignition off. Remove IAC valve from throttle Body. Connect IAC valve to IAC Driver Tool (J 37027-A). Hold finger over IAC pintle to avoid over extension. Using driver, retract and extend pintle. If IAC pintle moves steadily, go to step 6). If pintle does not move or movement is erratic, go to step 7).
  5. Check for faulty connection, open circuit or circuit shorted to ground or battery voltage. Repair as necessary. After repairs, go to step 8).
  6. Check IAC passage in throttle Body. Clean as necessary. After repairs, go to step 8).
  7. Replace IAC valve. After replacing IAC valve, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1508. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start engine. Using scan tool, command RPM from 500 to 1500 RPM. Repeat 2 times and exit from test. If RPM change responded to within 50 RPM with each command, see DIAGNOSTIC AIDS. If RPM does not respond as commanded, go to next step.
  3. Turn ignition off. Disconnect IAC harness connector and install IAC Node Light (J 37027-A). Start engine. Using scan tool, command RPM up to 1500 down to 500 and up to 1500 RPM, while observing node light. If node lights cycle Red and Green, but never off, go to next step. If node light LEDs do not cycle, go to step 5).
  4. Turn ignition off. Remove IAC valve from throttle Body. Connect IAC valve to IAC Driver Tool (J 37027-A). Hold finger over IAC pintle to avoid over extension. Using driver, retract and extend pintle. If IAC pintle moves steadily, go to step 6). If pintle does not move or movement is erratic, go to step 7).
  5. Check for faulty connection, open circuit or circuit shorted to ground or battery voltage. Repair as necessary. After repairs, go to step 8).
  6. Check IAC passage in throttle Body. Clean as necessary. After repairs, go to step 8).
  7. Replace IAC valve. After replacing IAC valve, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1509. 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).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, monitor A/C evaporator temperature. If scan tool reads 126°F (52°C), go to step 4). If scan tool does not read 126°F (52°C), go to next step.
  3. If scan tool reads 2°F (-17°C), go to step 5). If scan tool does not read as specified, see DIAGNOSTIC AIDS.
  4. Disconnect A/C evaporator temperature sensor harness connector. If scan tool reads 2°F (-17°C), go to step 16). If scan tool does not read as specified, go to step 13).
  5. Disconnect A/C evaporator temperature sensor harness connector. Using DVOM, check voltage from 5-volt reference circuit in sensor harness connector to battery ground. If DVOM reads 5 volts, go to next step. If voltage is not as specified, go to step 10).
  6. Check voltage between 5-volt reference circuit and ground circuit in sensor harness connector. If DVOM reads 5 volts, go to next step. If voltage is not as specified, go to step 11).
  7. Connect DVOM from 5-volt reference circuit in sensor harness connector to battery ground. Connect a fused jumper wire between ground and signal circuit in sensor harness connector. If DVOM reads 5 volts, go to next step. If voltage is not as specified, go to step 15).
  8. With fused jumper wire still connected, monitor A/C evaporator temperature with scan tool. If reading is 126°F (52°C), go to step 16). If reading is not as specified, go to next step.
  9. Using DVOM, check voltage between signal circuit and ground circuit in sensor harness connector. If DVOM reads zero volts, go to step 12). If DVOM does not read zero volts, go to step 14).
  10. Repair 5-volt reference circuit. After repairs, go to step 17).
  11. Repair open ground circuit. After repairs, go to step 17).
  12. Repair open signal circuit. After repairs, go to step 17).
  13. Repair signal circuit shorted to ground. After repairs, go to step 17).
  14. Repair signal circuit shorted to voltage. After repairs, go to step 17).
  15. Repair 5-volt reference and signal circuits shorted together. After repairs, go to step 17).
  16. Replace A/C evaporator temperature sensor. After repairs, 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 P1532. 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).
  18. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, monitor A/C evaporator temperature. If scan tool reads 126°F (52°C), go to step 4). If scan tool does not read as specified, go to next step.
  3. If scan tool reads 2°F (-17°C), go to step 5). If scan tool does not read as specified, see DIAGNOSTIC AIDS.
  4. Disconnect A/C evaporator temperature sensor harness connector. If scan tool reads 2°F (-17°C), go to step 16). If scan tool does not read as specified, go to step 13).
  5. Disconnect A/C evaporator temperature sensor harness connector. Using a DVOM, check voltage from 5-volt reference circuit in sensor harness connector to battery ground. If DVOM reads 5 volts, go to next step. If voltage is not as specified, go to step 10).
  6. Check voltage between 5-volt reference circuit and ground circuit in sensor harness connector. If DVOM reads 5 volts, go to next step. If voltage is not as specified, go to step 11).
  7. Connect DVOM from 5-volt reference circuit in sensor harness connector to battery ground. Connect a fused jumper wire between ground and signal circuit in sensor harness connector. If DVOM reads 5 volts, go to next step. If voltage is not as specified, go to step 15).
  8. With fused jumper wire still connected, monitor A/C evaporator temperature with scan tool. If reading is 126°F (52°C), go to step 16). If reading is not as specified, go to next step.
  9. Using DVOM, check voltage between signal circuit and ground circuit in sensor harness connector. If DVOM reads zero volts, go to step 12). If DVOM does not read zero volts, go to step 14).
  10. Repair 5-volt reference circuit. After repairs, go to step 17).
  11. Repair open ground circuit. After repairs, go to step 17).
  12. Repair open signal circuit. After repairs, go to step 17).
  13. Repair signal circuit shorted to ground. After repairs, go to step 17).
  14. Repair signal circuit shorted to voltage. After repairs, go to step 17).
  15. Repair 5-volt reference and signal circuits shorted together. After repairs, go to step 17).
  16. Replace A/C evaporator temperature sensor. After repairs, 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 P1533. 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).
  18. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and idle engine. Turn A/C off. Using scan tool, select ENGINE 1 DATA LIST and monitor A/C status display. If scan tool indicates A/C status as ON, go to step 4). If scan tool does not indicate that A/C status as ON, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1539. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition off. Remove A/C clutch relay. Start and idle engine for about 30 seconds. Using scan tool, select DTC INFO, FAIL THIS IGN. If scan tool indicates that DTC P1539 failed, go to next step. If scan tool does not indicate that DTC P1539 failed, go to step 6).
  5. Repair A/C clutch status circuit for short to battery voltage. After repairs, go to step 7).
  6. Replace AC clutch relay. After replacing relay, go to next step.
  7. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1539. 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).
  8. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

A/C status circuit goes to A/C compressor clutch and to A/C clutch relay. Check all circuits going to these components

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Install A/C manifold gauge set. If low side refrigerant pressure is more than 45 psi (3.2 kg/cm 2 ), go to next step. If refrigerant pressure is not as specified, diagnose A/C system. See the A/C-HEATER SYSTEM article.
  3. Turn ignition on, with engine off. Using scan tool, monitor A/C high side refrigerant pressure. Compare pressure reading on scan tool to reading on manifold gauge set. If both pressure readings are within 10 psi (.71 kg/cm 2 ) of each other, go to next step. If pressure reading is not as specified, go to step 6).
  4. Start engine. Turn A/C off for 10 seconds, then turn A/C on and wait for about 10 seconds. If DTC P0531 is set, diagnose DTC. If DTC P0531 is not set, diagnose A/C system. See the A/C-HEATER SYSTEM article.
  5. If A/C compressor clutch engages, diagnose A/C system using the A/C-HEATER SYSTEM article. If A/C compressor clutch does not engage, diagnose using the A/C COMPRESSOR CLUTCH CONTROLS article.
  6. Turn ignition off. Disconnect A/C refrigerant pressure sensor. Using a test light connected to battery voltage, probe sensor harness connector terminal "A". If test light illuminates, go to next step. If test light does not illuminate, go to step 10).
  7. Check connection at A/C refrigerant pressure sensor. Repair as necessary. After repairs, go to step 9). If connection is okay, go to next step.
  8. Replace A/C refrigerant pressure sensor.
  9. Repair connector.
  10. Repair open in A/C refrigerant pressure sensor ground circuit.

An A/C evaporator temperature sensor and/or A/C refrigerant pressure sensor with a shifted value could cause DTC to set.

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. 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 as commanded, go to next step. If relay does not turn on and off as commanded, go to step 5).
  3. Turn ignition off. Disconnect PCM containing relay control circuit. Turn ignition on. Using DVOM on 10-amp scale, measure current from relay control circuit in PCM harness connector to ground for 2 minutes. If current draw is less that .75 amp, but not zero, see DIAGNOSTIC AIDS. If current draw is not as specified, go to next step.
  4. Turn ignition off. Disconnect relay. Using DVOM, check resistance from relay control circuit in PCM connector to ground. If resistance is infinite, go to step 12). If resistance is not infinite, go to step 12).
  5. Turn ignition off. Disconnect relay. Connect test light between relay coil terminals in relay harness connector. Turn ignition on. Using scan tool, command relay on and off. If test light illuminates with each command, go to step 8). If test light does not illuminate with each command, go to next step.
  6. Connect test light to ground and probe battery feed circuits in relay harness connector. If test light illuminates on both terminals, go to next step. If test light does not illuminate on both terminals, go to step 11).
  7. Turn ignition off. Reconnect A/C relay. Disconnect PCM harness connector containing relay control circuit. Turn ignition on. Connect a fused jumper wire between ground and PCM connector (harness side), relay control circuit. If relay activates, go to step 9). If relay does not activate, go to step 10).
  8. Check connections at relay. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 12).
  9. Check connections at PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 13).
  10. Repair faulty relay control circuit. After repairs, go to step 14).
  11. Repair faulty battery feed circuit. After repairs, go to step 14).
  12. Replace A/C relay. After replacing relay, 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 DTC P1545. 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).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Start and idle engine with A/C on. If A/C clutch operates properly, go to next step. If A/C clutch does not operate, go to step 5).
  3. Using scan tool, select ENGINE 1 DATA LIST and monitor A/C status display. If scan tool indicates A/C status as ON, go to next step. If scan tool does not indicate that A/C status as ON, go to step 8).
  4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1546. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  5. Turn ignition off. Remove A/C clutch relay. Turn ignition on, with engine off. Using a test light connected to ground, probe ignition feed circuit at A/C relay terminal connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 9).
  6. Connect a fused jumper wire between ignition feed circuit and A/C clutch status circuit on A/C clutch relay harness. If A/C clutch engages, go to next step. If A/C clutch does not engage, go to step 10).
  7. Repair A/C clutch relay connection or replace faulty A/C clutch relay. After repairs, go to step 12).
  8. Repair open in A/C clutch status circuit from splice to PCM. After repairs, go to step 12).
  9. Repair open in ignition feed circuit to A/C relay. After repairs, go to step 12).
  10. Repair open in A/C status circuit from A/C relay to splice. After repairs, go to step 12).
  11. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1546. 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).
  13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, monitor traction control parameter. If scan tool displays ACTIVE, go to step 4). If scan tool does not display ACTIVE, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P1572. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect PCM connector C3. Turn ignition on. If scan tool displays ACTIVE, go to step 6). If scan tool does not display ACTIVE, go to next step.
  5. Check traction control active circuit for short to ground, or an EBTCM problem. After repairs, go to step 7).
  6. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  7. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1572. 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).
  8. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Crank engine. If engine starts and runs, see the TESTS W/O CODES article. If engine does not start, go to next step.
  3. If engine cranks, go to next step. If engine does not crank, diagnose theft deterrent system. See the ANTI-THEFT SYSTEM article in the ACCESSORIES/SAFETY EQUIPMENT section.
  4. Turn ignition off. Disconnect PCM connector. Connect a fused jumper wire between PCM connector, fuel enable signal circuit and a 5-volt source (IAT sensor terminal "B" will work). Using DVOM in Hertz (Hz) scale, connect DVOM to ground and PCM connector, fuel enable signal circuit. If DVOM reads 40-60 Hz, go to step 7). if reading is not as specified, go to next step.
  5. Check theft deterrent circuit for open, short to ground or short to battery voltage. Repair circuit as necessary. After repairs, go to step 9). If circuit is okay, go to next step.
  6. Replace theft deterrent module. After replacing module, go to step 9).
  7. Check PCM connector, fuel enable signal circuit for proper terminal tension. Repair as necessary. After repairs, go to step 9). If terminal is okay, go to next step.
  8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1626. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If engine starts and then stalls, indicates that portion of theft deterrent module, which generates signal to PCM is not operating or circuit between theft deterrent module and PCM is open or shorted to ground. If theft deterrent module is found to be okay, PCM may be at fault, but this not a likely condition.

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.).

Ignition voltage is supplied directly to Fan Control (FC) relay coil. PCM controls relay by grounding control circuit through an internal switch called a driver. primary function of 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 on control circuit should be low (near zero). When PCM is commanding a component off, voltage of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other that what is expected, fault line will change causing DTC to set.

Relay is used to control high current flow to A/C compressor clutch, allowing PCM driver to only have to handle relatively low current used by relay.

DTC will set when following conditions are present

  1. DTCs P0117, P0118 or P1539 not set.
  2. Engine speed more than 600 RPM.
  3. PCM detects commanded state of driver and actual state do not match.
  4. Conditions met for 5 seconds.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command FC relay on and off. If relay turns on and off as commanded, go to next step. If relay does not turn on an off as commanded, go to step 5).
  3. Turn ignition off. Disconnect PCM containing relay control circuit. Turn ignition on. Using DVOM on 10-amp scale, measure current from relay control circuit in PCM harness connector to ground for 2 minutes. If current draw is less that .75 amp but not zero, see DIAGNOSTIC AIDS. If current draw is not as specified, go to next step.
  4. Turn ignition off. Disconnect relay. Using DVOM, check resistance from relay control circuit in PCM connector to ground. If resistance is infinite, go to step 10). If resistance is not infinite, go to step 12).
  5. Turn ignition off. Disconnect FC relay. Connect test light between relay coil terminals in relay harness connector. Turn ignition on. Using scan tool, command relay on and off. If test light illuminates with each command, go to step 8). If test light does not illuminate with each command, go to next step.
  6. Connect test light to ground and probe battery feed circuits in relay harness connector. If test light illuminates on both terminals, go to next step. If test light does not illuminate on both terminals, go to step 11).
  7. Turn ignition off. Reconnect FC relay. Disconnect PCM harness connector containing relay control circuit. Turn ignition on. Connect a fused jumper wire between ground and PCM connector (harness side), relay control circuit. If relay activates, go to step 9). If relay does not activate, go to step 10).
  8. Check connections at relay. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 12).
  9. Check connections at PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 13).
  10. Repair faulty relay control circuit. After repairs, go to step 14).
  11. Repair faulty battery feed circuit. After repairs, go to step 14).
  12. Replace FC relay. After replacing relay, go to step 14).
  13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, 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 DTC P1641. 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).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Disconnect relay No. 2. Turn ignition on. Using scan tool, command FC relay on and off. If relay turns on and off as commanded, go to next step. If relay does not turn on an off as commanded, go to step 5).
  3. Turn ignition off. Disconnect PCM containing relay control circuit. Turn ignition on. Using DVOM on 10-amp scale, measure current from relay control circuit in PCM harness connector to ground for 2 minutes. If current draw is less than .75 amp but not zero, go to step 8). If current draw is not as specified, go to next step.
  4. Turn ignition off. Disconnect relay. Using DVOM, check resistance from relay control circuit in PCM connector to ground. If resistance is infinite, go to step 16). If resistance is not infinite, go to step 14).
  5. Turn ignition off. Disconnect FC relay. Connect test light between relay coil terminals in relay harness connector. Turn ignition on. Using scan tool, command relay on and off. If test light illuminates with each command, go to step 12). If test light does not illuminate with each command, go to next step.
  6. Connect test light to ground and probe battery feed circuits in relay harness connector. If test light illuminates on both terminals, go to next step. If test light does not illuminate on both terminals, go to step 15).
  7. Turn ignition off. Reconnect FC relay. Disconnect PCM harness connector containing relay control circuit. Turn ignition on. Connect a fused jumper wire between ground and PCM connector (harness side), relay control circuit. If relay activates, go to step 13). If relay does not activate, go to step 16).
  8. Reconnect relay No. 2. Disconnect relay No. 3. Connect DVOM on 10-amp scale from relay control circuit in PCM harness connector to ground. If relay activates, go to next step. If relay does not activate, go to step 10).
  9. Using DVOM on 10-amp scale, measure current from relay control circuit in PCM harness connector to ground for 2 minutes. If current draw is less than .75 amp but not zero, see DIAGNOSTIC AIDS. If current draw is not as specified, go to step 16).
  10. Turn ignition off. Disconnect FC relay. Connect test light between relay coil terminals in relay harness connector. Turn ignition on. Connect DVOM on 10-amp scale from relay control circuit in PCM harness connector to ground. If test light illuminates, go to step 12). If test light does not illuminate, go to next step.
  11. Connect test light to ground and probe ignition feed circuit in relay harness. If test light illuminates, go to step 14). If test light does not illuminate, go to step 15).
  12. Check connections at relay. Repair as necessary. After repairs, go to step 18). If connections are okay, go to step 16).
  13. Check connections at PCM. Repair as necessary. After repairs, go to step 18). If connections are okay, go to step 17).
  14. Repair faulty relay control circuit. After repairs, go to step 18).
  15. Repair faulty ignition feed circuit. After repairs, go to step 18).
  16. Replace relay. After replacing relay, go to step 18).
  17. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  18. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1642. 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).
  19. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. With engine running, observe is vehicle tachometer is indicating engine RPM. If RPM is indicated, see DIAGNOSTIC AIDS. If RPM is not indicated, go to next step.
  3. Turn ignition off. Disconnect PCM connector. Install Signal Generator Tester (J 33431-B) to engine speed output circuit of PCM harness connector terminal and ground. Turn ignition on. Turn tester on and set tester to generate a tachometer signal. If vehicle tachometer indicates an RPM reading, go to next step. If tachometer does not indicate an RPM reading, check tachometer circuit to instrument panel.
  4. Check for faulty PCM connections. Repair as necessary. After repairs, go to step 6). If connections are okay, go to next step.
  5. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1643. 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).
  7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition off. Raise drive wheel. Start engine. Disable ASR/TCS system (if equipped). Start and operate engine at idle. Place transmission in gear. If speedometer indicates vehicle speed, see DIAGNOSTIC AIDS. If speedometer does not indicate vehicle speed, go to next step.
  3. Turn ignition off. Disconnect PCM connector C2. Install Signal Generator Tester (J 33431-B) to VSS output circuit of PCM harness connector and ground. Turn ignition on. Turn tester on and set tester to generate vehicle speed signal. If vehicle speedometer indicates vehicle speed, go to next step. If speedometer does not indicate vehicle speed, check speedometer assembly in instrument panel.
  4. Check for faulty PCM connections. Repair as necessary. After repairs, go to step 6). If connections are okay, go to next step.
  5. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1652. 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).
  7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command relay on and off. If relay turns on and off as commanded, go to next step. If relay does not run on and off as commanded, go to step 5).
  3. Turn ignition off. Disconnect PCM connector containing relay control circuit. Turn ignition on. Using DVOM on 10-amp scale, check current from relay control circuit in PCM harness connector to ground for 2 minutes. Current draw should be less than .75 amp, but not zero. If current draw is as specified, see DIAGNOSTIC AIDS. If current draw is not as specified, go to next step.
  4. Turn ignition off. Disconnect relay. Using DVOM, check resistance from relay control circuit in PCM harness connector to ground. If resistance is infinite, go to step 12). If resistance is not infinite, go to step 10).
  5. Turn ignition off. Disconnect relay. Connect test light between relay coil terminals in relay harness connector. Turn ignition on. Using scan tool, command 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.
  6. Connect test light to ground and probe ignition feed circuit in relay harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
  7. Turn ignition off. Reconnect relay. Disconnect PCM connector containing relay control circuit. Turn ignition on. Connect a fused jumper wire between ground and PCM connector (harness side), relay control circuit. If relay activates, go to step 9). If relay does not activate, go to step 10).
  8. Check connections at relay. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 12).
  9. Check connections at PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 13).
  10. Repair faulty relay control circuit. After repairs, go to step 14).
  11. Repair faulty relay ignition feed circuit. After repairs, go to step 14).
  12. Replace faulty relay. After replacing relay, 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 DTC P1657. 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).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command MIL on and off. If MIL turns on and off with each command, see DIAGNOSTIC AIDS. If MIL does not turn on and off with each command, go to next step.
  3. Turn ignition off. Disconnect PCM connector containing light control circuit. Turn ignition on. If MIL illuminates, go to step 5). If MIL does not illuminate, go to next step.
  4. Connect a fused jumper wire between ground and MIL control circuit in PCM harness connector. If MIL illuminates, go to step 6). If MIL does not illuminate, go to step 7).
  5. Repair short to ground in MIL control circuit. After repairs, go to step 9).
  6. Check PCM connections. Repair as necessary. After repairs, go to step 9). If connections are okay, go to step 8).
  7. Check for faulty light bulb, open ignition feed to bulb, open control circuit or circuit shorted to battery voltage. Repair as necessary. After repairs, go to step 9).
  8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1661. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

If ignition feed circuit is suspected of being open, check if other bulbs on that circuit illuminate.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command upshift light on and off. If shift light turns on and off with each command, see DIAGNOSTIC AIDS. If light does not turn on and off with each command, go to next step.
  3. Turn ignition off. Disconnect PCM connector containing light control circuit. Turn ignition on. If shift light illuminates, go to step 5). If shift light does not illuminate, go to next step.
  4. Connect a fused jumper wire between ground and shift light control circuit in PCM harness connector. If shift light illuminates, go to step 6). If shift light does not illuminate, go to step 7).
  5. Repair short to ground in upshift light control circuit. After repairs, go to step 9).
  6. Check PCM connections. Repair as necessary. After repairs, go to step 9). If connections are okay, go to step 8).
  7. Check for faulty light bulb, open ignition feed to bulb, open control circuit or circuit shorted to battery voltage. Repair as necessary. After repairs, go to step 9).
  8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1664. 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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 the «BASIC TESTING - 5.7L»(ref-20656) article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command solenoid on and off. If solenoid turns on and off with each command, go to next step. If solenoid does not turn on and off with each command, go to step 5).
  3. Turn ignition off. Disconnect PCM harness connector containing solenoid control circuit. Turn ignition on. Using DVOM on 10-amp scale, check current from solenoid control circuit in PCM harness connector to ground for 2 minutes. If current draw is less than 1.5 amps but not zero, see DIAGNOSTIC AIDS. If current draw is not as specified, go to next step.
  4. Turn ignition off. Disconnect solenoid. Using DVOM, check resistance from solenoid control circuit in PCM harness connector and ground. If resistance is infinite, go to step 12). If resistance is not as specified, go to step 10).
  5. Turn ignition off. Disconnect solenoid. Connect test light between solenoid harness connector terminals. Turn ignition on. Using scan tool, command solenoid on and off. If test light illuminates with each command, go to step 8). If test light does not illuminate with each command, go to next step.
  6. Using test light connected to ground, probe ignition feed circuit in solenoid harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
  7. Turn ignition off. Reconnect solenoid. Disconnect PCM connector containing solenoid control circuit. Turn ignition on. Connect a fused jumper wire between ground and solenoid control circuit in PCM harness connector. If solenoid activates, go to step 9). If solenoid does not activate, go to step 10).
  8. Check connections at solenoid. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 12).
  9. Check PCM connections. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 13).
  10. Repair faulty solenoid control circuit. After repairs, go to step 14).
  11. Repair faulty solenoid ignition feed circuit. After repairs, go to step 14).
  12. Replace solenoid. After replacing solenoid, 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 DTC P1667. 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).
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

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.).

Low system voltage can cause DTC to set. When reviewing captured data, check if low system voltage condition is present at time DTC is stored in memory.

More articles — Engine Control System - Tests W/codes - 5.7L