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Home/Mitsubishi/Eclipse/Mitsubishi Eclipse III (1999-2005)/Repair manual/Testing & Diagnostics/Engine Controls - Self Diagnostics - 2.4L: Other
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Engine Controls - Self Diagnostics - 2.4L: Other Mitsubishi Eclipse III

Testing & Diagnostics 6 illustrations ~5292 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, then go out. When ECM/PCM determines an emissions related malfunction exists, ECM/PCM will turn the MIL on. If ECM/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 ECM/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 ECM/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 OBD-II DRIVE CYCLES under VERIFYING REPAIRS . DO NOT run drive cycle if outside air temperature is less than 14°F (-10°C).

Failure Management

When main sensor malfunctions are detected, ECM/PCM will enter fail-safe mode. Default values will be substituted in ECM/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 ECM/PCM. This will erase any DTCs stored in ECM/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 ECM/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, ECM/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 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 ECM/PCM to monitor the fault. Clear DTCs and drive vehicle according to appropriate monitor. See appropriate monitor under OBD-II 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 ECM/PCM ran monitor and found no faults, readiness test status will display COMPLETE or READY. Repair is verified.

If ECM/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 ECM/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 ECM/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 re-selecting 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.

CATALYTIC CONVERTER MONITOR

This monitor applies to DTC P0421. 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 for A/T.

Monitor takes about 20 minutes to complete. This drive must be completed twice. To run monitor, use illustration. (Scheme 169) Perform steps as follows

Scheme 169

Scheme 169
Scheme 169
  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 5 minutes or more while keeping speed at 45-60 MPH (5th gear on M/T).
  5. Fully close throttle and decelerate to 35-40 MPH.
  6. While keeping accelerator pedal opening degree constant (4th gear on M/T), keep speed at 35-40 MPH for 90 seconds or more (this is when monitor runs).
  7. Fully close throttle and decelerate for 10 seconds. Then, quickly accelerate until speed is 35-40 MPH. Then repeat steps 6 and 7 five more times.
  8. Return vehicle to shop and turn ignition off.

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 75°F (30°C) or less.
  2. Atmospheric temperature is 41-113°F (5-45°C).
  3. Selector lever is in "D" range.
  4. Test may not run if fuel tank is over 2/3 full.

Monitor takes about 8 minutes to complete. This drive must be completed twice. To run monitor, use illustration. (Scheme 170) 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 3 minutes and 20 seconds or more while keeping speed at 55-60 MPH (5th gear on M/T).
  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.

Scheme 170

Scheme 170
Scheme 170

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 A/T.
  4. A/C switch is in OFF position.

Monitor takes about 10 minutes to complete. This drive must be completed twice. To run monitor, use illustration. (Scheme 171) 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 the engine.
  3. Accelerate until the vehicle speed reaches 35-40 mph.
  4. Travel for 20 seconds or more while keeping the vehicle speed at 35-40 mph (M/T: 4th speed).
  5. Fully close the throttle from an engine speed of 2000-3000 RPM, and while keeping the clutch engaged, decelerate to approximately 900 RPM without applying the brakes. Do not steer the handle or turn the light ON/OFF during this time. (During monitor).
  6. Accelerate until the vehicle speed reaches 35-40 mph, and travel for 20 seconds or more (M/T: 4th speed). Then, repeat steps 5 and 6 for eight monitor sessions.
  7. Return the vehicle to the shop and turn the ignition off.

Scheme 171

Scheme 171
Scheme 171

FUEL TRIM MONITOR

This monitor applies to DTCs P0171 and P0172. 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 A/T.

Monitor takes about 35 minutes to complete. This drive must be completed twice. To run monitor, use illustration. (Scheme 172) 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 the engine.
  3. Accelerate until the vehicle speed is 55-60 mph.
  4. Travel for 30 minutes or more while keeping the vehicle speed at 55-60 mph (M/T: 5th speed). Carry out one gradual deceleration/acceleration returning to 55-60 mph within 120 seconds (during monitor).
  5. Return the vehicle to the shop and turn the ignition off.

Scheme 172

Scheme 172
Scheme 172

HEATED OXYGEN SENSOR MONITOR

This monitor applies to DTCs P0133 and P0139. 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 A/T.

Monitor takes about 5 minutes to complete. This drive must be completed twice. To run monitor, use illustration. (Scheme 173) 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 the engine.
  3. Accelerate until the vehicle speed is 35-40 mph.
  4. While keeping the accelerator pedal opening degree constant (M/T: 4th speed), keep the vehicle speed at 35-40 mph and travel for 120 seconds or more (during monitor).
  5. Return vehicle to shop and turn ignition off.

Scheme 173

Scheme 173
Scheme 173

OTHER MONITOR

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 A/T.

Monitor takes about 10 minutes to complete. This drive must be completed twice. To run monitor, use illustration. (Scheme 174) 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 (4th gear on M/T).
  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 transaxle must be in "P" range. After idling for 5 minutes, turn ignition off.

Scheme 174

Scheme 174
Scheme 174

SUMMARY

If no 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

A battery positive voltage is applied on the data link connector power terminal (terminal 16). The ground terminals (terminal 4, 5) are grounded to the vehicle body.

Note. The cause of the fault is probably a defect in power supply system (including ground) for the on-board diagnostic test mode line. The most likely causes for this case are malfunction of the data link connector or a damaged harness wire.

  1. Measure the voltage between terminal 16 and ground. see scheme 32 If the voltage shows normal (battery positive voltage), go to step 3, otherwise go to next step.
  2. Check harness connectors C-108, C-113 and C-89 at intermediate connector for damage, and repair or replace as required. If intermediate connectors are in good condition, repair harness wire between fusible link (2) and data link connector C-29, terminal 16 because of open circuit. Then confirm that the malfunction symptom is eliminated.
  3. Check for continuity between terminals 4, 5 and ground (the resistance should be less than 2 ohms). If the continuity is normal, replace the scan tool and confirm that the malfunction symptom has been eliminated. If the continuity is not normal, repair harness wire between data link connector C-29, terminal 4, 5 and ground because of open circuit or harness damage. Confirm that the malfunction has been eliminated.

No Communication With Engine Control Module/Powertrain Control Module

  1. Turn ignition off. Check Engine Control Module (ECM) connector C-56 or Powertrain Control Module (PCM) connector C-57 for loose, damaged or corroded terminals. see scheme 15or see scheme 33. If problem exists, repair 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 ECM connector C-56, terminal No. 56 or PCM connector C-57, terminal No. 84. see scheme 15, see scheme 32 or see scheme 33. 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 Red/White wire between OBD-II DLC terminal No. 7 and ECM connector C-56, terminal No. 62 or PCM connector C-57, terminal No. 85. If problem exists, repair Red/White wire. If problem does not exist, go to next step.
  4. Remove MFI relay from engine compartment relay box. Check MFI relay connector for loose, damaged or corroded terminals. If problem exists, repair 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. 3 and 4. see scheme 31 If battery voltage exists at both terminals, go to next step. If battery voltage does not exist at either or both terminals, repair Red/White wire between engine compartment relay box fuse No. 13 (20-amp) and MFI relay.
  7. Disconnect ECM connector C-60 or PCM connector C-57. Check ECM connector C-60 or PCM connector C-57 for loose, damaged or corroded terminals. If problem exists, repair connector. If problem does not exist, go to next step.
  8. Turn ignition on. Measure voltage between ground and ECM connector C-60, terminal No. 82 (Black/White wire) or PCM connector C-57, terminal No. 98 (Black/White wire). see scheme 15or see scheme 33. If battery voltage exists, go to next step. If battery voltage does not exist, check Black/White wire between ignition switch and ECM/PCM. If problem exists, repair wiring between ignition switch and ECM/PCM. If problem does not exist, check ignition switch. Repair as necessary.
  9. Turn ignition off. On A/T vehicle, disconnect PCM connector C-54. On all vehicles, measure voltage between ground and ECM connector C-60, terminal No. 80 (Orange/Black wire) or PCM connector C-54, terminal No. 66 (Orange/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair Orange/Black wire between engine compartment relay box fuse No. 4 (10-amp) and PCM.
  10. On M/T vehicle, disconnect ECM connector C-49. On all vehicles, measure resistance between ground and ECM connector C-49, terminals No. 13 (Black wire) and No. 26 (Black wire) or PCM connector C-54, terminals No. 42 (Black wire) and No. 48 (Black wire). If each resistance is less than 2 ohms, go to next step. If either resistance is 2 ohms or more, repair Black wire(s) between ground and ECM/PCM.
  11. On M/T vehicle, disconnect ECM connector C-53. On all vehicles, measure voltage between ground and ECM connector C-53, terminal No. 38 (White/Violet wire) or PCM connector C-54, terminal No. 49 (White/Violet wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair White/Violet wire between ECM/PCM and MFI relay.
  12. Connect jumper wire between ground and ECM connector C-53, terminal No. 38 (White/Violet wire) or PCM connector C-54, terminal No. 49 (White/Violet wire). MFI relay should audibly click. Measure voltage between ground and ECM connector C-49, terminals No. 12 (Red wire) and No. 25 (Red wire) or PCM connector C-54, terminals No. 41 (Red wire) and No. 47 (Red wire). If battery voltage exists at each terminal, replace ECM/PCM. If battery voltage does not exist at either terminal, repair appropriate Red wire between MFI relay and ECM/PCM.

Malfunction Indicator Light (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. Remove MFI relay from engine compartment relay box. Check MFI relay connector for loose, damaged or corroded terminals. If problem exists, repair 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, install MFI relay and go to next step.
  4. Measure voltage between ground and MFI relay connector terminals No. 3 and 4. see scheme 31 If battery voltage exists at both terminals, go to next step. If battery voltage does not exist at either or both terminals, repair Red/White wire between engine compartment relay box fuse No. 13 (20-amp) and MFI relay.
  5. Disconnect ECM connector C-60 or PCM connector C-57. Check ECM connector C-60 or PCM connector C-57 for loose, damaged or corroded terminals. If problem exists, repair connector. If problem does not exist, go to next step.
  6. Turn ignition on. Measure voltage between ground and ECM connector C-60, terminal No. 82 (Black/White wire) or PCM connector C-57, terminal No. 98 (Black/White wire). see scheme 15or see scheme 33. If battery voltage exists, go to next step. If battery voltage does not exist, check Black/White wire between ignition switch and ECM/PCM. If problem exists, repair wiring between ignition switch and ECM/PCM. If problem does not exist, check ignition switch. Repair as necessary.
  7. Turn ignition off. Measure voltage between ground and ECM connector C-60, terminal No. 80 (Orange/Black wire) or PCM connector C-54, terminal No. 66 (Orange/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair Orange/Black wire between engine compartment relay box fuse No. 4 (10-amp) and ECM/PCM.
  8. Check for continuity between ground and ECM connector C-49 terminals No. 13 (Black wire) and No. 26 (Black wire) or PCM connector C-54 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(s) between ground and ECM/PCM.
  9. On M/T vehicle, disconnect ECM connector C-53. On all vehicles, measure voltage between ground and ECM connector C-53, terminal No. 38 (White/Violet wire) or PCM connector C-54, terminal No. 49 (White/Violet wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair White/Violet wire between ECM/PCM and MFI relay.
  10. On M/T vehicle, disconnect ECM connector C-49. On all vehicles, connect jumper wire between ground and ECM connector C-53, terminal No. 38 (White/Violet wire) or PCM connector C-54, terminal No. 49 (White/Violet wire). MFI relay should audibly click. Measure voltage between ground and ECM connector C-49 terminals No. 12 (Red wire) and No. 25 (Red wire) or PCM connector C-54 terminals No. 41 (Red wire) and No. 47 (Red wire). If battery voltage exists at each terminal, replace ECM/PCM. If battery voltage does not exist at either terminal, repair appropriate Red wire between MFI relay and ECM/PCM.
  11. Check for burned out bulb. If bulb is blown, replace bulb. If bulb is okay, go to next step.
  12. Disconnect combination meter (instrument cluster) connector C-41. Check combination meter connector C-41 for loose, damaged or corroded terminals. If problem exists, repair connector. If problem does not exist, go to next step.
  13. Turn ignition on. Measure voltage between ground and combination meter connector C-41, terminal No. 52 (Black/White wire). see scheme 11 If battery voltage exists, go to next step. If battery voltage does not exist, repair Black/White wire or Green wire between combination meter and ignition switch.
  14. Turn ignition off. Reconnect combination meter connector. Disconnect ECM connector C-53 or PCM connector C-50. Check ECM connector C-53 or PCM connector C-50 for loose, damaged or corroded terminals. If problem exists, repair connector. If problem does not exist, go to next step.
  15. Turn ignition on. Measure voltage between ground and ECM connector C-53, terminal No. 36 (Red/Yellow wire) or PCM connector C-50, terminal No. 22 (Red/Yellow wire). see scheme 15or see scheme 33. If battery voltage exists, replace ECM/PCM. If battery voltage does not exist, repair Red/Yellow wire between combination meter connector and ECM/PCM.

MIL Stays On

  1. Using scan tool, check for stored DTCs. See «ENTERING ON-BOARD DIAGNOSTICS»(ref-156203-S06222357072003072200000) under SELF-DIAGNOSTIC SYSTEM. If DTCs are present, record all DTCs and go to appropriate test(s) under «DIAGNOSTIC TESTS»(ref-156203-S01801692972003071000000). If no DTCs are present, go to next step.
  2. Turn ignition off. Disconnect combination meter (instrument cluster) connector C-41. see scheme 11 Check for continuity between ground and combination meter connector C-41, terminal No. 41 (Red/Yellow wire). If continuity exists, repair short to ground in Red/Yellow wire between combination meter and ECM/PCM. If continuity does not exist, replace ECM/PCM.

Probable Causes

  1. Volume air flow sensor failed.
  2. Open or shorted volume air flow sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  5. Air leak between volume air flow sensor and throttle body.
  1. Volume air flow sensor failed.
  2. Open or shorted volume air flow sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  5. Air leak between volume air flow sensor and throttle body.
  1. Barometric pressure sensor failed.
  2. Open or shorted barometric pressure sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Barometric pressure sensor failed.
  2. Open or shorted barometric pressure sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Barometric pressure sensor failed.
  2. Open or shorted barometric pressure sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Intake air temperature sensor failed.
  2. Open or shorted intake air temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Intake air temperature sensor failed.
  2. Open or shorted intake air temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Intake air temperature sensor failed.
  2. Open or shorted intake air temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Engine coolant temperature sensor failed.
  2. Open or shorted engine coolant temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Engine coolant temperature sensor failed.
  2. Open or shorted engine coolant temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Engine coolant temperature sensor failed.
  2. Open or shorted engine coolant temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Throttle position sensor failed or maladjusted.
  2. Open or shorted throttle position sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Throttle position sensor failed or maladjusted.
  2. Open or shorted throttle position sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Throttle position sensor failed or maladjusted.
  2. Open or shorted throttle position sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Engine coolant temperature sensor failed.
  2. Open or shorted engine coolant temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. The thermostat is faulty.
  2. ECM (M/T) failed.
  3. PCM (A/T) failed.
  1. Heated oxygen sensor (front) deteriorated.
  2. Open circuit in heated oxygen sensor (front) output line.
  3. Open circuit in heated oxygen sensor (front) ground line.
  4. ECM failed (M/T).
  5. PCM failed (A/T).
  1. Heated oxygen sensor (front) deteriorated.
  2. ECM failed (M/T).
  3. PCM failed (A/T).
  1. Heated oxygen sensor (front) deteriorated.
  2. Open circuit in heated oxygen sensor (front) output line.
  3. Open circuit in heated oxygen sensor (front) ground line.
  4. Heated oxygen sensor (rear) deteriorated. NOTE: When the heated oxygen sensor (front) begins to deteriorate, the heated oxygen sensor output voltage will deviate from the voltage when the sensor was new (normally 0.5 volt at stoichiometric ratio). This deviation will be corrected by the heated oxygen sensor (rear). If the heated oxygen sensor (rear) responds poorly because it has deteriorated, it will improperly correct the heated oxygen sensor (front). Thus, even when closed loop control is being effected, the fluctuation of the heated oxygen sensor (front) output voltage decreases, without intersecting with 0.5 volt. As a result, there is a possibility of DTC P0134 becoming registered.
  5. ECM failed (M/T).
  6. PCM failed (A/T).
  1. Open or shorted heated oxygen sensor (front) heater circuit.
  2. Open circuit in heated oxygen sensor (front) heater.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Heated oxygen sensor (rear) failed.
  2. Short circuit in heated oxygen sensor (rear) output line.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Heated oxygen sensor (rear) failed.
  2. Open circuit in heated oxygen sensor (rear) output line.
  3. Open circuit in heated oxygen sensor (rear) ground line.
  4. ECM failed (M/T).
  5. PCM failed (A/T).
  1. Heated oxygen sensor (rear) failed.
  2. ECM failed (M/T).
  3. PCM failed (A/T).
  1. Open or shorted heated oxygen sensor (rear) heater circuit.
  2. Open circuit in heated oxygen sensor (rear) heater.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Volume air flow sensor failed.
  2. Injector failed.
  3. Incorrect fuel pressure.
  4. Air drawn in from gaps in gasket, seals, etc.
  5. Heated oxygen sensor failed.
  6. Engine coolant temperature sensor failed.
  7. Intake air temperature sensor failed.
  8. Barometric pressure sensor failed.
  9. Use of incorrect or contaminated fuel.
  10. ECU failed (M/T).
  11. PCM failed (A/T).
  1. Volume air flow sensor failed.
  2. Injector failed.
  3. Incorrect fuel pressure.
  4. Heated oxygen sensor failed.
  5. Engine coolant temperature sensor failed.
  6. Intake air temperature sensor failed.
  7. Barometric pressure sensor failed.
  8. Exhaust leak.
  9. Use of incorrect or contaminated fuel.
  10. ECM failed (M/T).
  11. PCM failed (A/T).
  1. Fuel temperature sensor failed.
  2. Open or shorted fuel temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T). NOTE: A diagnostic trouble code (DTC) could be output if the engine coolant is changed as indicated below. Because this is not a failure, the DTC must be erased. Make sure to test drive the vehicle in accordance with the drive cycle pattern in order to verify that a DTC will not be output.
  5. The engine and the radiator have been flushed repeatedly when the engine coolant temperature was high (or the fuel temperature was high).
  1. Fuel temperature sensor failed.
  2. Open or shorted fuel temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Fuel temperature sensor failed.
  2. Open or shorted fuel temperature sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Injector failed.
  2. Open or shorted injector circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Ignition system related part(s) failed.
  2. Poor crankshaft position sensor.
  3. Incorrect air/fuel ratio.
  4. Low compression pressure.
  5. Skipping of timing belt teeth.
  6. EGR system and EGR valve failed.
  7. ECM failed (M/T).
  8. PCM failed (A/T).
  1. Ignition system related part(s) failed.
  2. Low compression pressure.
  3. Injector failed.
  4. ECM failed (M/T).
  5. PCM failed (A/T).
  1. Knock sensor failed.
  2. Open or shorted knock sensor circuit, or loose connector.
  3. ECM (M/T) failed.
  4. PCM (A/T) failed.
  1. Crankshaft position sensor failed.
  2. Open or shorted crankshaft position sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Camshaft position sensor failed.
  2. Open or shorted camshaft position sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. EGR valve does not open.
  2. EGR control vacuum is too low.
  3. EGR solenoid failed.
  4. Open or shorted EGR solenoid circuit, or loose connector.
  5. Manifold differential pressure sensor failed.
  6. ECM failed (M/T).
  7. PCM failed (A/T).
  1. EGR solenoid failed.
  2. Open or shorted EGR solenoid circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Catalytic converter deteriorated.
  2. Heated oxygen sensor failed.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Evaporative emission purge solenoid failed.
  2. Evaporative emission ventilation solenoid failed.
  3. Choking up of hose between evaporative emission canister and evaporative emission ventilation solenoid.
  1. Loose fuel cap.
  2. Fuel cap relief pressure is incorrect.
  3. Evaporative emission canister seal is faulty.
  4. Fuel tank, purge line or vapor line seal faded.
  5. Evaporative emission ventilation solenoid failed.
  1. Evaporative emission purge solenoid failed.
  2. Open or shorted evaporative emission purge solenoid circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Evaporative emission ventilation solenoid failed.
  2. Open or shorted evaporative emission ventilation solenoid circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Fuel tank differential pressure sensor failed.
  2. Damaged harness in the fuel tank differential pressure sensor circuit.
  3. ECM (M/T) or PCM (A/T) failed.
  1. Fuel tank differential pressure sensor failed.
  2. Open fuel tank differential pressure sensor circuit, or loose connector.
  3. ECM (M/T) or PCM (A/T) failed.
  1. Fuel tank differential pressure sensor failed.
  2. Open fuel tank differential pressure sensor circuit, or loose connector.
  3. ECM (M/T) or PCM (A/T) failed.
  1. Loose fuel cap.
  2. Fuel cap relief pressure is incorrect.
  3. Fuel overflow limiter valve failed.
  4. Purge line or vapor line is clogged.
  5. Fuel tank, purge line or vapor line seal failed.
  6. Evaporative emission purge solenoid failed.
  7. Evaporative emission ventilation solenoid failed.
  8. Fuel tank differential pressure sensor failed.
  9. Evaporative emission canister seal is faulty.
  10. Evaporative emission canister is clogged.
  1. Loose fuel cap.
  2. Fuel cap relief pressure is incorrect.
  3. Evaporative emission canister seal is faulty.
  4. Fuel tank, purge line or vapor line seal failed.
  5. Evaporative emission ventilation solenoid valve failed.
  1. Fuel gauge unit failed.
  2. Open or shorted fuel gauge unit circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Vehicle speed sensor failed.
  2. Open or shorted vehicle speed sensor circuit, or loose connector.
  3. ECM failed.
  1. Idle air control motor failed.
  2. Open or shorted idle air control motor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Idle air control motor failed.
  2. Open or shorted idle air control motor circuit, or loose connector.
  3. ECM failed (M/T)
  4. PCM failed (A/T)
  1. Power steering pressure switch failed.
  2. Open or shorted power steering pressure switch circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Manifold differential pressure sensor failed.
  2. Open or shorted manifold differential pressure sensor circuit, or loose connector.
  3. ECM failed (M/T).
  4. PCM failed (A/T).
  1. Open circuit in generator FR terminal circuit.
  2. ECM failed (M/T).
  3. PCM failed (A/T).
  1. Open or shorted battery backup line, or loose connector.
  2. ECM failed (M/T).
  3. PCM failed (A/T).

Note. When the engine is started with the IOD or storage connector disconnected, the ECU (M/T) or PCM (A/T) judges that an open circuit has occurred in the battery backup line. Consequently, the service engine soon/malfunction indicator lamp illuminates and the DTC is stored in memory.

  1. Malfunction of harness or connector.
  2. Malfunction of immobilizer-ECU.
  3. Malfunction of ECM (M/T) or PCM (A/T).

More articles — Engine Controls - Self Diagnostics - 2.4L