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Home/Mitsubishi/Montero/Mitsubishi Montero III (1999-2006)/Repair manual/Testing & Diagnostics/Engine Controls - Self-Diagnostics: Other
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Engine Controls - Self-Diagnostics: Other Mitsubishi Montero III

Testing & Diagnostics 6 illustrations ~5101 words

Malfunction Indicator Light (MIL)

MIL may also be referred to as Service Engine Soon light. If all systems are normal, immediately after ignition switch is turned on, MIL will illuminate for 5 seconds. Go out. When PCM determines an emissions related malfunction exists, PCM will turn the MIL on. If PCM determines that the malfunction no longer exists, it will turn the MIL off.

If MIL will not come on for bulb check or MIL stays on with no Diagnostic Trouble Codes (DTCs) present, diagnose MIL circuit malfunction. See MALFUNCTION INDICATOR LIGHT (MIL) under DIAGNOSTIC CIRCUIT CHECK.

Freeze Frame Data

The conditions at the time a malfunction is detected will be stored in PCM as freeze frame data. While multiple DTCs may be recorded, only one freeze frame is recorded. DTCs are assigned a priority with fuel and misfire codes having the highest priority. Non-emissions related DTCs have the lowest priority. The DTC with the highest priority will be the one recorded in freeze frame. Freeze frame records are cleared when DTCs are erased. Freeze frame data recorded is

  1. Engine Coolant Temperature
  2. Engine RPM
  3. Vehicle Speed
  4. Long Term Fuel Trim (Displayed As Percent)
  5. Short Term Fuel Trim (Displayed As Percent)
  6. Fuel Control Condition (Open Or Closed Loop)
  7. Calculated Load Value (Displayed As Percent)
  8. DTC During Data Recording

OBD-II Drive Cycles

Manufacturer defines drive cycle as a pattern of driving that meets code set criteria for PCM to monitor a particular system/component. Drive cycle is used to verify repair by reproducing conditions during which fault occurred. There are 6 different drive cycles. These are; Catalytic Converter Monitor, EVAP System Leak Monitor, Heated Oxygen Sensor (HO2S) Monitor, EGR Monitor, Fuel Trim Monitor and Other Monitor. For the requirements to run a drive cycle, see appropriate drive cycle in DRIVE CYCLES . DO NOT run drive cycle if outside air temperature is less than 14°F (-10°C).

Failure Management

When main sensor malfunctions are detected, PCM will enter fail-safe mode. Default values will be substituted in PCM calculations for faulty sensor.

SERVICE PRECAUTIONS

Before proceeding with diagnosis, following precautions must be observed

  1. Ensure vehicle has a fully charged battery and functional charging system. Codes cannot be retrieved if battery voltage is too low.
  2. Visually inspect connectors and circuit wiring being worked on.
  3. DO NOT disconnect battery or PCM. This will erase any DTCs stored in PCM.
  4. DO NOT cause short circuits when performing electrical tests. This will set additional DTCs, making diagnosis of original problem more difficult.
  5. DO NOT use a test light in place of a voltmeter. Use voltmeter with 10-megohm impedance.
  6. When checking for spark, ensure coil wire is NOT more than 1/4" from chassis ground. If coil wire is more than 1/4" from chassis ground, damage to vehicle electronics and/or PCM may result.
  7. DO NOT prolong testing of fuel injectors. Engine may hydrostatically (liquid) lock.

VERIFYING REPAIRS

Note. Erasing DTCs will also erase freeze frame data and reset readiness test status.

Procedure for verifying repairs depends on scan tool functions and whether DTC is set by one-trip or two-trip fault detection logic. Two-trip fault detection logic requires fault be detected on 2 consecutive drive cycles, which each meet code set criteria, before DTC will set and MIL will illuminate. DTCs using one-trip fault detection logic set DTC the first time fault is detected. If fault is emissions related, PCM will also turn on MIL. Most DTCs use two-trip fault detection logic. To determine which logic is used to set DTC, see DIAGNOSTIC TROUBLE CODE INDEX table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. Then, go to appropriate repair verification procedure.

VERIFYING REPAIRS FOR ONE-TRIP DTCS

Note freeze frame data. Clear DTCs. Drive vehicle in manner approximating conditions recorded in freeze frame in order to verify repair. Using scan tool, check for DTCs.

VERIFYING REPAIRS FOR TWO-TRIP DTCS

For catalytic converter, Heated Oxygen Sensor (HO2S), EGR, fuel trim and Evaporative Emissions (EVAP) system related DTCs, it will be necessary to drive vehicle according to drive cycle that allows PCM to monitor the fault. Clear DTCs and drive vehicle according to appropriate monitor. See appropriate monitor under DRIVE CYCLES .

If drive cycle used to verify repair runs catalytic converter monitor, HO2S monitor, EGR monitor, fuel trim monitor or EVAP system leak monitor, repair may be verified in one drive cycle by checking readiness test status. Readiness test status is an indicator showing whether monitor has run or not run. If PCM ran monitor and found no faults, readiness test status will display COMPLETE or READY. Repair is verified.

If PCM found fault during drive cycle, or monitor did not meet criteria to run, readiness test status will display INCOMPLETE or NOT READY. Perform drive cycle again. The second time drive cycle is run, readiness test status will display COMPLETE or READY whether or not a fault was found. It will be necessary to check for DTCs. If readiness test status does not display COMPLETE or READY after 2 drive cycles, one or both drive cycles failed to meet criteria necessary for PCM to run monitor.

For systems and components monitored by Other Monitor, record freeze frame data. Clear DTCs. Drive vehicle in manner approximating conditions recorded in freeze frame in order to verify repair.

Other monitor does not have readiness test status because Other Monitor runs continuously. Manufacturer's MUT-II Scan Tool (MB991502) provides mode 2 (increased sensitivity) and mode 5 (provisional DTCs) functions which allow repairs to be verified after one drive cycle. Generic scan tools may or may not have these functions. If scan tool does not have these functions, drive vehicle under conditions approximating freeze frame data twice, then check for DTCs.

MUT-II scan tool mode 2 (increased sensitivity) allows single drive cycle testing of emissions related DTCs. Mode 2 commands PCM to illuminate MIL and set DTC on first occurrence of fault when code set criteria are being met. If MIL does not illuminate during drive cycle, repair is verified. Return to mode 1 (normal) by turning ignition off or reselecting mode 1. When scan tool returns to mode 1, freeze frame data, readiness test status and DTCs are erased.

MUT-II scan tool mode 5 (provisional DTCs) can be used to verify repairs after only one drive cycle by reporting fault as provisional (pending) DTC. Mode 5 is limited to reporting faults related to misfire, fuel system and faults detected by Other Monitor.

Note. DO NOT run drive cycle if outside air temperature is less than 14°F (-10°C).

Catalytic Converter Monitor

This monitor applies to DTCs P0421 and P0431. Following conditions must be met during the test

  1. Atmospheric temperature is 14°F (-10°C) or more.
  2. A/C switch is in OFF position.
  3. Selector lever is in "D" range.

Monitor takes about 20 minutes to complete. To run monitor, use illustration. (Scheme 50) Perform steps as follows

  1. Remove all test equipment from vehicle and install all components and connectors that were removed or disconnected during testing.
  2. Start engine.
  3. Accelerate to 45 MPH.
  4. Travel 300 seconds or more while keeping speed at 45-60 MPH.
  5. Decelerate to 35-40 MPH.
  6. While keeping accelerator pedal opening degree constant, keep speed at 35-40 MPH for 90 seconds or more.
  7. Fully close throttle and decelerate for 10 seconds. Then, quickly accelerate until speed is 35-40 MPH. Then repeat steps 5 and 6 five more times.
  8. Return vehicle to shop and turn ignition off. Confirm DTC P0421 or P0431 is not set. If either DTC is set, refer to specific Warm Up Catalyst Efficiency Below Threshold in DIAGNOSTIC TESTS. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-135490-S24068601682002022200000) for directions.

Scheme 50

Scheme 50
Scheme 50

EVAP System Leak Monitor

This monitor applies to DTCs P0441, P0442, P0451, P0452, P0453, P0455 and P0456. Following conditions must be met during the test

  1. Engine coolant temperature must be 113°F (45°C) or less.
  2. Atmospheric temperature is 41-113°F (5-45°C).
  3. Selector lever is in "D" range.

Monitor takes about 8 minutes to complete. To run monitor, use illustration. (Scheme 51) Perform steps as follows

  1. Remove all test equipment from vehicle and install all components and connectors that were removed or disconnected during testing.
  2. Start engine.
  3. Accelerate to 55-60 MPH.
  4. Travel for 200 seconds or more while keeping speed at 55-60 MPH.
  5. While keeping accelerator pedal position constant, keep speed at 55-60 MPH for 150 seconds or more (this is when monitor runs).
  6. Return vehicle to shop and turn ignition off. Confirm that DTC is not set. If DTCs P0441, P0442, P0451, P0452, P0453, P0455 or P0456 is set, refer to specific EVAP Emission Control System procedure in DIAGNOSTIC TESTS. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-135490-S24068601682002022200000) for directions.

Scheme 51

Scheme 51
Scheme 51

EGR Monitor

This monitor applies to DTC P0401. Following conditions must be met during the test

  1. Engine coolant temperature must be 176°F (80°C) or more.
  2. Atmospheric temperature is 41°F (5°C) or more.
  3. Selector lever is in "D" range.
  4. A/C switch is in OFF position.

Monitor takes about 10 minutes to complete. To run monitor, use illustration. (Scheme 52) Perform steps as follows

  1. Remove all test equipment from vehicle and install all components and connectors that were removed or disconnected during testing.
  2. After engine is completely warmed up, turn ignition off.
  3. Start engine and quickly accelerate to 35-40 MPH.
  4. Keep speed constant at 35-40 MPH for 20 seconds or more.
  5. Decelerate by closing throttle fully and allowing engine speed to drop from 2000-3000 RPM to about 900 RPM. DO NOT apply brakes. DO NOT turn steering wheel or operate light switch during this time.
  6. Accelerate to 35-40 MPH, then hold speed constant for 20 seconds or more. Repeat steps 4 and 5 seven more times.
  7. Return vehicle to shop and turn ignition off. Confirm that DTC P0401 is not set. If DTC P0401 is set, refer to specific Exhaust Gas Recirculation Insufficient Flow detected in DIAGNOSTIC TESTS. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-135490-S24068601682002022200000) for directions.

Scheme 52

Scheme 52
Scheme 52

Fuel Trim Monitor

This monitor applies to DTCs P0171, P0172, P0174 and P0175. Following conditions must be met during the test

  1. Engine coolant temperature is 176-207°F (80-97°C).
  2. Atmospheric temperature is 14-140°F (-10-60°C).
  3. Selector lever is in "D" range.

Monitor takes about 35 minutes to complete. To run monitor, use illustration. (Scheme 53) Perform steps as follows

  1. Remove all test equipment from vehicle and install all components and connectors that were removed or disconnected during testing.
  2. After engine is completely warmed up, turn ignition off.
  3. Start engine and quickly accelerate to 55-60 MPH.
  4. Drive at 55-60 MPH for 30 minutes or more. During this period DO NOT drive at constant speed for more than 120 seconds. Carry out gradual deceleration and acceleration within every 120 second time frame.
  5. Return vehicle to shop and turn ignition off. Confirm that DTC is not set. If DTCs P0171, P0172, P0174 or P0175 is set, refer to specific System Too Rich or System Too Lean procedure in DIAGNOSTIC TESTS. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-135490-S24068601682002022200000) for directions.

Scheme 53

Scheme 53
Scheme 53

Heated Oxygen Sensor Monitor

This monitor applies to DTCs P0132, P0133, P0137, P0138, P0139, P0152, P0153, P0158 and P0159. Following conditions must be met during the test

  1. Engine coolant temperature must be 176°F (80°C) or more.
  2. Atmospheric temperature is 14°F (-10°C) or more.
  3. Selector lever is in "D" range.

Monitor takes about 5 minutes to complete. To run monitor, use illustration. (Scheme 54) Perform steps as follows

  1. Remove all test equipment from vehicle and install all components and connectors that were removed or disconnected during testing.
  2. After engine is completely warmed up, turn ignition off.
  3. Start engine and quickly accelerate to 35-40 MPH.
  4. While keeping accelerator pedal position constant, keep speed at 35-40 MPH for 120 seconds or more.
  5. Return vehicle to shop and turn ignition off. Confirm that DTC is not set. If DTCs P0132, P0133, P0137, P0138, P0139, P0152, P0153, P0158 or P0159 is set, refer to specific HO2S Circuit Malfunction procedure in DIAGNOSTIC TESTS. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-135490-S24068601682002022200000) for directions.

Scheme 54

Scheme 54
Scheme 54

Other Monitor

Note. The Other Monitor passively monitors for opens, shorts, grounds and out of range sensor parameters. It runs continuously.

This monitor applies to DTCs not covered by the rest of the monitors. Following conditions must be met during the test

  1. Engine coolant temperature must be 176°F (80°C) or more.
  2. Atmospheric temperature is 41°F (5°C) or more.
  3. Selector lever is in "D" range.

Monitor takes about 10 minutes to complete. To run monitor, use illustration. (Scheme 55) Perform steps as follows

  1. Remove all test equipment from vehicle and install all components and connectors that were removed or disconnected during testing.
  2. After engine is completely warmed up, turn ignition off.
  3. Start engine and quickly accelerate to 35-40 MPH.
  4. Drive for 5 minutes or more at 35-40 MPH.
  5. Return vehicle to shop and let idle. While engine is idling, A/C switch must be in OFF position, lights and accessories must be off, steering wheel must be straight ahead, and automatic transmission must be in "P" range. After idling for 5 minutes, turn ignition off. Confirm that DTCs are not set. If DTCs are set, refer to specific DTC and troubleshoot problem in DIAGNOSTIC TESTS. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-135490-S24068601682002022200000) for directions.

Scheme 55

Scheme 55
Scheme 55

SUMMARY

If there are no DTCs, or provisional codes, and driveability symptoms exist, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures. See INTERMITTENT DIAGNOSTIC TROUBLE CODES .

No Communication With All Systems

  1. Turn ignition off. Measure voltage between ground and OBD-II Data Link Connector (OBD-II DLC) terminal No. 16 (White wire). see scheme 27 If battery voltage exists, go to next step. If battery voltage does not exist, repair or replace connectors and/or wiring between OBD-II DLC and fusible link No. 1 (60-amp) in engine compartment relay box.
  2. Check for continuity between ground and OBD-II DLC terminals No. 4 (Black wire) and No. 5 (Black wire). If continuity exists at each terminal, repair or replace scan tool as necessary. If continuity does not exist at either terminal, repair wiring between ground and OBD-II DLC.

No Communication With Powertrain Control Module (PCM)

  1. Turn ignition off. Check PCM connector D-109 for loose, damaged, or corroded terminals. see scheme 28 If problem exists, repair or replace connector. If problem does not exist, go to next step.
  2. Check for open or short to ground in Gray/Red wire between OBD-II DLC terminal No. 1 and PCM connector D-109 terminal No. 84. see scheme 27and see scheme 28. If problem exists, repair Gray/Red wire. If problem does not exist, go to next step.
  3. Check for open or short to ground in wire between OBD-II DLC terminal No. 7 (Red/White wire) and PCM connector D-109 terminal No. 85 (Green/Orange wire). If problem exists, repair Red/White wire or Green/Orange wire. If problem does not exist, go to next step.
  4. Remove MFI relay. see scheme 4 Check MFI relay connector for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. If problem does not exist, go to next step.
  5. Check MFI relay. See «FUEL PUMP RELAY & MFI RELAY»(ref-135493-S16727418372002022200000) under RELAYS under MOTORS, RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING article. If problem exists, replace MFI relay. If problem does not exist, install MFI relay and go to next step.
  6. Measure voltage between ground and MFI relay connector terminals No. 2 and 3. see scheme 26 If battery voltage exists at both terminals, go to next step. If battery voltage does not exist at either or both terminals, repair White/Black wire between MFI relay connector and fusible link No. 6 (20-amp) located in engine compartment relay box.
  7. Disconnect PCM connector D-109. Check PCM connector D-109 for loose, damaged, or corroded terminals. If problem exists, repair or replace connector as necessary. If problem does not exist, go to next step.
  8. Turn ignition on. Measure voltage between ground and PCM connector D-109 terminal No. 98 (Blue/Black wire). see scheme 28 If battery voltage exists, go to next step. If battery voltage does not exist, check Blue/Black wire between ignition switch and PCM. If problem exists, repair Blue/Black between ignition switch and PCM. If problem does not exist, check ignition switch. Repair as necessary.
  9. Turn ignition off. Disconnect PCM 26-pin connector D-108. Measure voltage between ground and PCM connector D-108 terminal No. 66 (Red/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair Red/Black wire between PCM and fuse No. 7 (10-amp), located in engine compartment relay box.
  10. Check for continuity between ground and PCM connector D-108 terminals No. 42 (Black wire) and No. 48 (Black wire). If continuity exists at each terminal, go to next step. If continuity does not exist at either terminal, repair appropriate Black wire between ground and PCM.
  11. Measure voltage between ground and PCM connector D-108 terminal No. 49 (White/Blue wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair White/Blue wire between PCM and MFI relay.
  12. Connect jumper wire between ground and PCM connector D-108 terminal No. 49 (White/Blue wire). MFI relay should audibly click. Measure voltage between ground and PCM connector D-108 terminals No. 41 (Red wire) and No. 47 (Red wire). If battery voltage exists at each terminal, replace PCM. If battery voltage does not exist at either terminal, repair appropriate Red wire between MFI relay and PCM.

MIL Does Not Come On

  1. Using scan tool, check data list item No. 16 (power supply voltage). If battery voltage exists, go to step 11. If battery voltage does not exist, go to next step.
  2. Turn ignition off. Remove MFI relay. see scheme 4 Check MFI relay connector for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. If problem does not exist, go to next step.
  3. Check MFI relay. See «FUEL PUMP RELAY & MFI RELAY»(ref-135493-S16727418372002022200000) under RELAYS under MOTORS, RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING article. If problem exists, replace MFI relay. If problem does not exist, go to next step.
  4. Measure voltage between ground and MFI relay connector terminals No. 2 and 3. see scheme 26 If battery voltage exists at both terminals, go to next step. If battery voltage does not exist at either or both terminals, repair White/Black wire between MFI relay and fusible link No. 6 (20-amp), located in engine compartment relay box.
  5. Disconnect PCM 28-pin connector D-109. Check PCM connector D-109 for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. If problem does not exist, go to next step.
  6. Turn ignition on. Measure voltage between ground and PCM connector D-109 terminal No. 98 (Blue/Black wire). see scheme 28 If battery voltage exists, go to next step. If battery voltage does not exist, check Blue/Black wire between ignition switch and PCM. If problem exists, repair wiring between ignition switch and PCM. If problem does not exist, check ignition switch. Repair as necessary.
  7. Turn ignition off. Disconnect PCM 26-pin connector D-108. Measure voltage between ground and PCM connector D-108 terminal No. 66 (Red/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair Red/Black wire between PCM and fusible link No. 2 (120-amp), located in engine compartment relay box.
  8. Check for continuity between ground and PCM connector D-108 terminals No. 42 (Black wire) and No. 48 (Black wire). If continuity exists at each terminal, go to next step. If continuity does not exist at either terminal, repair appropriate Black wire between ground and PCM.
  9. Measure voltage between ground and PCM connector D-108 terminal No. 49 (White/Blue wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair White/Blue wire between PCM and MFI relay.
  10. Connect jumper wire between ground and PCM connector D-108 terminal No. 49 (White/Blue wire). MFI relay should audibly click. Measure voltage between ground and PCM connector D-108 terminals No. 41 (Red wire) and No. 47 (Red wire). If battery voltage exists at each terminal, replace PCM. If battery voltage does not exist at either terminal, repair appropriate Red wire between MFI relay and PCM.
  11. Check for burned out bulb. If bulb is blown, replace bulb. If bulb is okay, go to next step.
  12. Check combination meter connectors D-03 and D-04 for loose, damaged, or corroded terminals. If problem exists, repair appropriate connector. If problem does not exist, go to next step.
  13. Disconnect combination meter connector D-03. Turn ignition on. Measure voltage between ground and combination meter connector D-03 terminal No. 62 (Black/White wire). see scheme 13 If battery voltage exists, go to next step. If battery voltage does not exist, repair Black/White wire between combination meter and ignition switch.
  14. Turn ignition off. Reconnect combination meter connector D-03. Disconnect PCM 35-pin connector D-107. Check PCM connector D-107 for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. If problem does not exist, go to next step.
  15. Turn ignition on. Measure voltage between ground and PCM connector D-107 terminal No. 22 (Red/White wire). see scheme 28 If battery voltage exists, replace PCM. If battery voltage does not exist, repair Red/White wire between combination meter connector D-04 and PCM.

Malfunction Indicator Light (MIL) Stays On

  1. Using scan tool, check for stored DTCs. See «ENTERING ON-BOARD DIAGNOSTICS»(ref-135490-S22711304562002022200000) under SELF-DIAGNOSTIC SYSTEM. If DTCs are present, record all DTCs and go to appropriate test(s) under «DIAGNOSTIC TESTS»(ref-135490-S26872682292002022200000). If no DTCs are present, go to next step.
  2. Turn ignition off. Disconnect combination meter (instrument cluster) connector D-04. Check for continuity between ground and combination meter connector D-04 terminal No. 38 (Red/White wire). see scheme 14 If continuity exists, repair short to ground in Red/White wire between combination meter and PCM. If continuity does not exist, replace PCM.

Probable Cause

  1. VAF sensor failed.
  2. Open or short in VAF sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  4. Air leak between VAF sensor and throttle body.
  1. VAF sensor failed.
  2. Open or short in VAF sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  4. Air leak between VAF sensor and throttle body.
  1. BARO sensor failed.
  2. Open or short in BARO circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. BARO sensor failed.
  2. Open or short in BARO circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. BARO sensor failed.
  2. Open or short in BARO circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. IAT sensor failed.
  2. Open or short in IAT sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. IAT sensor failed.
  2. Open or short in IAT circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. IAT sensor failed.
  2. Open or short in IAT circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. Engine Coolant Temperature (ECT) sensor failed.
  2. Open or short in ECT sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. Engine Coolant Temperature (ECT) sensor failed.
  2. Open or short in ECT sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. Engine Coolant Temperature (ECT) sensor failed.
  2. Open or short in ECT sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. TP sensor failed or misadjusted.
  2. Open or short in TP sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. TP sensor failed or misadjusted.
  2. Open or short in TP sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. TP sensor failed or misadjusted.
  2. Open or short in TP sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. Engine coolant temperature (ECT) sensor failed.
  2. Open or shorted engine coolant temperature (ECT) sensor circuit or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. Faulty thermostat.
  2. Powertrain Control Module (PCM) failed.
  1. Right front HO2S deteriorated.
  2. Open circuit in right front HO2S output or ground wire.
  3. PCM failed.

Probable Causes

  1. Right front HO2S deteriorated.
  2. PCM failed.
  1. Right front HO2S deteriorated.
  2. Open circuit in right front HO2S output or ground wire.
  3. PCM failed.
  4. Right rear HO2S deteriorated.

Note. When the right front HO2S begins to deteriorate, the HO2S output voltage will deviate from the voltage when the sensor was new. This deviation will be corrected by the right rear HO2S. If the right rear HO2S responds poorly because it has deteriorated, it will improperly correct the right front HO2S. Even when closed loop control is being effected, the fluctuation of the right front HO2S output voltage decreases, without intersecting with 0.5 volt. This will result in DTC P0134 being set.

  1. Short in right front HO2S heater circuit.
  2. Open circuit in right front HO2S heater.
  3. Powertrain Control Module (PCM) failed.
  1. Right rear HO2S failed.
  2. Short circuit in right rear HO2S output line.
  3. Powertrain Control Module (PCM) failed.
  1. Right rear HO2S failed.
  2. Open circuit in right rear HO2S output line or ground line.
  3. Powertrain Control Module (PCM) failed.
  1. Right rear HO2S failed.
  2. Powertrain Control Module (PCM) failed.
  1. Open or short in right rear HO2S heater circuit.
  2. Open circuit in right rear HO2S heater.
  3. Powertrain Control Module (PCM) failed.
  1. Left front HO2S deteriorated.
  2. Open circuit in left front HO2S output line or ground line.
  3. Powertrain Control Module (PCM) failed.
  1. Left front HO2S deteriorated.
  2. Powertrain Control Module (PCM) failed.
  1. Left front HO2S deteriorated.
  2. Open circuit in left front HO2S output line or ground line.
  3. Powertrain Control Module (PCM) failed.
  4. Left rear HO2S deteriorated.

Note. When the left front HO2S begins to deteriorate, the HO2S output voltage will deviate from the voltage when the sensor was new. This deviation will be corrected by the left rear HO2S. If the left rear HO2S responds poorly because it has deteriorated, it will improperly correct the left front HO2S. Even when closed loop control is being effected, the fluctuation of the left front HO2S output voltage decreases, without intersecting with 0.5 volt. This will result in DTC P0154 being set.

  1. Open or short in left front HO2S heater circuit.
  2. Open circuit in left front HO2S heater.
  3. Powertrain Control Module (PCM) failed.
  1. Left rear HO2S failed.
  2. Short circuit in left rear HO2S output line.
  3. Powertrain Control Module (PCM) failed.
  1. Left rear HO2S failed.
  2. Open circuit in left rear HO2S output line or ground line.
  3. Powertrain Control Module (PCM) failed.
  1. Left rear HO2S failed.
  2. Powertrain Control Module (PCM) failed.
  1. Open or short in left rear HO2S heater circuit.
  2. Open in left rear HO2S heater.
  3. Powertrain Control Module (PCM) failed.
  1. VAF sensor failed.
  2. Fuel injector No. 1, 3, or 5 failed.
  3. Incorrect fuel pressure.
  4. Air intake system leak.
  5. Right bank Heated Oxygen Sensor (HO2S) failed.
  6. Engine Coolant Temperature (ECT) sensor failed.
  7. Intake Air Temperature (IAT) sensor failed.
  8. Barometric Pressure (BARO) sensor failed.
  9. Exhaust system leak.
  10. Incorrect or contaminated fuel used.
  11. Powertrain Control Module (PCM) failed.
  1. VAF sensor failed.
  2. Fuel injector No. 1, 3, or 5 failed.
  3. Incorrect fuel pressure.
  4. Air intake system leak.
  5. Right bank Heated Oxygen Sensor (HO2S) failed.
  6. Engine Coolant Temperature (ECT) sensor failed.
  7. Intake Air Temperature (IAT) sensor failed.
  8. Barometric Pressure (BARO) sensor failed.
  9. Exhaust system leak.
  10. Incorrect or contaminated fuel used.
  11. Powertrain Control Module (PCM) failed.
  1. VAF sensor failed.
  2. Fuel injector No. 2, 4, or 6 failed.
  3. Incorrect fuel pressure.
  4. Air intake system leak.
  5. Left bank Heated Oxygen Sensor (HO2S) failed.
  6. Engine Coolant Temperature (ECT) sensor failed.
  7. Intake Air Temperature (IAT) sensor failed.
  8. Barometric Pressure (BARO) sensor failed.
  9. Exhaust system leak.
  10. Incorrect or contaminated fuel used.
  11. Powertrain Control Module (PCM) failed.
  1. VAF sensor failed.
  2. Fuel injector No. 2, 4, or 6 failed.
  3. Incorrect fuel pressure.
  4. Air intake system leak.
  5. Left bank Heated Oxygen Sensor (HO2S) failed.
  6. Engine Coolant Temperature (ECT) sensor failed.
  7. Intake Air Temperature (IAT) sensor failed.
  8. Barometric Pressure (BARO) sensor failed.
  9. Exhaust system leak.
  10. Incorrect or contaminated fuel used.
  11. Powertrain Control Module (PCM) failed.
  1. Fuel temperature sensor failed.
  2. Open or shorted fuel temperature sensor circuit, or loose connector.
  3. PCM failed.

Note. A DTC could be output if the engine and radiator have been flushed repeatedly when the engine coolant temperature was high (or fuel temperature was high). Because this is not a failure, erase the DTC. Then test drive vehicle following OBD-II drive cycle Other Monitor pattern. See OTHER MONITOR under OBD-II DRIVE CYCLES under VERIFYING REPAIRS. Check for DTCs. Verify DTC is not output.

  1. Fuel temperature sensor failed.
  2. Open or shorted fuel temperature sensor circuit, or loose connector.
  3. PCM failed.
  1. Fuel temperature sensor failed.
  2. Open or shorted fuel temperature sensor circuit or loose connector.
  3. PCM failed.
  1. Fuel injector failed.
  2. Open or short in fuel injector circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. Ignition system related part(s) failed.
  2. Poor CKP sensor signal.
  3. Incorrect air/fuel ratio.
  4. Low compression pressure.
  5. Timing belt jumped.
  6. EGR system failed.
  7. Powertrain Control Module (PCM) failed.
  1. Ignition related part(s) failed.
  2. Low compression.
  3. Fuel injector failed.
  4. Powertrain Control Module (PCM) failed.
  1. Knock sensor failed.
  2. Open or short in knock sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. CKP sensor failed.
  2. Open or short in CKP sensor, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. CMP sensor malfunction.
  2. Open or short in CMP sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. EGR valve does not open.
  2. EGR control vacuum is too low.
  3. EGR solenoid failed.
  4. Open or short in EGR solenoid circuit, or loose connector.
  5. Manifold Differential Pressure (MDP) sensor failed.
  6. Powertrain Control Module (PCM) failed.
  1. EGR solenoid failed.
  2. Open or short in EGR solenoid circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. Catalytic converter deteriorated.
  2. HO2S failed.
  3. Powertrain Control Module (PCM) failed.
  1. EVAP emission purge solenoid failed.
  2. EVAP emission ventilation solenoid failed.
  3. Choked or clogged hose between EVAP canister and EVAP emission ventilation solenoid.
  1. Improperly installed or missing fuel cap.
  2. Fuel cap relief pressure is incorrect.
  3. EVAP canister leaks.
  4. Fuel overflow limiter valve failed.
  5. Fuel tank, purge line or vapor line leaks.
  6. EVAP system ventilation solenoid failed.
  1. Purge solenoid failed.
  2. Open or short in purge solenoid circuit, or loose connector.
  3. PCM failed.
  1. Ventilation solenoid failed.
  2. Open or short in ventilation solenoid circuit, or loose connector.
  3. PCM failed.
  1. Fuel Tank Differential Pressure (FTDP) sensor failed.
  2. Open or short in FTDP sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  4. Blocked fuel vapor lines.
  1. Loose fuel cap.
  2. Defective fuel cap relief valve, or incorrect relief pressure.
  3. Fuel overflow limiter valve failed.
  4. Purge line or vapor line is clogged.
  5. Fuel tank, purge line or vapor line leaks.
  6. Purge solenoid failed.
  7. Ventilation solenoid failed.
  8. Fuel Tank Differential Pressure (FTDP) sensor failed.
  9. Clogged or leaking EVAP canister.
  1. Fuel gauge unit failed.
  2. Open or shorted fuel gauge unit circuit, or loose connector.
  3. PCM failed.
  1. Idle Air Control (IAC) motor failed.
  2. Open or short in IAC motor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. Power steering pressure switch failed.
  2. Open or short in power steering pressure switch circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. MDP sensor failed.
  2. Open or short in MDP sensor circuit, or loose connector.
  3. Powertrain Control Module (PCM) failed.
  1. Open or shorted battery backup line, or loose connector.
  2. PCM failed.
  1. Wiring malfunction.
  2. Immobilizer ECU malfunction.
  3. PCM malfunction.

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