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Engine Controls - Self-Diagnostics - Millenia 2.3L: Other Mazda Millenia I рестайлинг

Testing & Diagnostics 4 illustrations ~7077 words

Pending Codes

Pending codes appear when a problem is detected in a monitored system. The Malfunction Indicator Light (MIL) is illuminated when a problem is detected in 2 consecutive drive cycles. The pending code is stored in Powertrain Control Module (PCM) during the first drive cycle when a failed system is detected. If a system does not fail during the second drive cycle, PCM concludes that system has returned to normal or problem was mistakenly detected, and deletes pending code. If system failure is detected during a second drive mode, PCM concludes that suspect system has failed, deletes pending code, illuminates MIL and stores Diagnostic Trouble Codes (DTC).

Condition

MIL comes on and stays on. Possible causes are

  1. Power Control Module (PCM) illuminates MIL for emission-related problem (DTCs stored in PCM).
  2. Short circuit between MIL and PCM.

FREEZE FRAME DATA

Freeze frame data is technical data which indicates engine's condition at time of first malfunction. This data will remain in memory even if another emission-related DTC is stored, with the exception of misfire or fuel system DTCs. Once freeze frame data for misfire or fuel system DTC is stored, it will overwrite any previous data after which the freeze frame data will not be overwritten again.

Apply parking brake. Place shift lever in Park (A/T) or Neutral (M/T). Block wheels. Turn off all electrical accessories. Ensure engine is at normal operating temperature.

Perform visual inspection. Ensure air cleaner and inlet ducts are clean, and system wiring harness is properly connected. Check for bent or broken connector terminals and corroded or loose wires. Check Powertrain Control Module (PCM), sensors and actuators for physical damage. Check engine coolant for proper level and mixture. Check for proper transmission fluid level and quality.

Turn ignition off. Ensure proper memory card, EPROM, is inserted into NGS scan tool. Connect service connections of adapter cable to vehicle Data Link Connector (DLC) and NGS scan tool. see scheme 1 Connect NGS scan tool power supply cable to power and listen for a double beep to indicate scan tool is on.

To access freeze frame data, program scan tool using the following steps

  1. Select GENERIC OBD II FUNCTIONS.
  2. Select CONT.
  3. Select FREEZE FRAME DATA.
  4. Select TRIGGER and follow scan tool prompts.

If system did not store any FREEZE FRAME DATA DTCs, scan tool will display NO TRIGGER CODE SET.

PCM Adaptive Memory Drive Mode

  1. Using scan tool, check RFCFLAG PID data status. If RFCFLAG PID data is on, procedure is complete, PCM has adaptive memory. If RFCFLAG PID data is off, perform following procedure before performing EGR monitor repair verification drive mode or HO2S/TWC monitor repair verification drive mode.
  2. Start engine and warm to normal operating temperature. Ensure all accessories are off. Ensure ignition timing and idle speed are within specification. Adjust as necessary. See BASIC DIAGNOSTIC PROCEDURES article. Ensure nothing is connected to DLC. Increase engine RPM to specified speed. (Scheme 36)
  3. Operate engine at specified RPM for minimum of 15 seconds. Idle engine until engine cooling fan stops. Idle engine for 20 seconds after engine cooling fan has stopped. Using scan tool, monitor PID data for RPM, FAN2 (with A/C) and FAN1 (without A/C). Turn ignition off and on. Using scan tool, check RFCFLAG PID data to confirm PCM adaptive memory status. If RFCFLAG PID data is on, procedure is complete, PCM has adaptive memory. If RFCFLAG PID data is off, go back to previous step.

Scheme 36

Scheme 36
Scheme 36

EGR Monitor Repair Verification Drive Mode

  1. Using scan tool, check RFCFLAG PID data status. If RFCFLAG PID data is off, perform PCM adaptive memory drive mode first and go to next step. See «PCM ADAPTIVE MEMORY DRIVE MODE»(ref-11774-S36254338772001040500000). If RFCFLAG PID data is on, go to next step.
  2. Start engine and warm to normal operating temperature. Ensure all accessories are off.
  3. Drive vehicle at specified speeds. (Scheme 37) Stop vehicle and access ON BOARD SYSTEM READINESS menu of GENERIC OBD II FUNCTIONS to check drive mode completion status. RFC should change to YES when test is complete. If test is not complete, turn ignition off and repeat this step. If test is complete, go to next step.
  4. Check test results in DIAGNOSTIC MONITORING TEST RESULTS menu of GENERIC OBD II FUNCTIONS. If results are okay (MEAS are within specification), ensure no DTCs are present. If no DTCs are present, repairs are complete. If results are not okay (MEAS are not within specification), repairs are not complete.

Scheme 37

Scheme 37
Scheme 37

HO2S/TWC Monitor Repair Verification Drive Mode

  1. Using scan tool, check RFCFLAG PID data status. If RFCFLAG PID data is off, perform PCM adaptive memory drive mode first and go to next step. See «PCM ADAPTIVE MEMORY DRIVE MODE»(ref-11774-S36254338772001040500000). If RFCFLAG PID data is on, go to next step.
  2. Start engine and warm to normal operating temperature. Ensure all accessories are off.
  3. Drive vehicle at specified speeds. (Scheme 38) Stop vehicle and access ON BOARD SYSTEM READINESS menu of GENERIC OBD II FUNCTIONS to check drive mode completion status. RFC should change to YES when test is complete. If test is not complete, turn ignition off and repeat this step. If test is complete, go to next step.
  4. Check test results in DIAGNOSTIC MONITORING TEST RESULTS menu of GENERIC OBD II FUNCTIONS. If results are okay (MEAS are within specification), ensure no DTCs are present. If no DTCs are present, repairs are complete. If results are not okay (MEAS are not within specification), repairs are not complete.

Scheme 38

Scheme 38
Scheme 38

EVAP Monitor Repair Verification Drive Mode

Note. If EVAP monitor repair verification drive mode cannot be performed because vehicle cannot be driven during conditions specified for this test, perform evaporative system test procedure as an alternative. See SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE & 626 article.

  1. Ensure following conditions are met: Engine coolant temperature is 14°F (-10°C). Intake air temperature is 14-131°F (-10-55°C). Barometric pressure is 72 kPa. Fuel Tank Level (FTL) PID V data is.5-2.5 volts. Ensure all accessories are off.
  2. Start and operate engine at 3500 RPM to warm to normal operating temperature. Operate vehicle as specified. (Scheme 39) Stop vehicle and access ON BOARD SYSTEM READINESS menu of GENERIC OBD II FUNCTIONS to check drive mode completion status. RFC should change to YES when test is complete. If test is not complete, turn ignition off and repeat this step. If test is complete, go to next step.
  3. Check test results in DIAGNOSTIC MONITORING TEST RESULTS menu of GENERIC OBD II FUNCTIONS. If results are okay (MEAS value of 10:21:00 and 10:22:00 are within specification), ensure no DTCs are present. If no DTCs are present, repairs are complete. If results are not okay (MEAS value of 10:21:00 and 10:22:00 are not within specification), repairs are not complete.

Scheme 39

Scheme 39
Scheme 39

SUMMARY

If no diagnostic trouble code is present but driveability problem still is present, proceed to TROUBLE SHOOTING - NO CODES article for symptom diagnosis or intermittent diagnostic procedures.

DTC is set when input voltage from MAF sensor is less than .64 volt or greater than 4.9 volts with engine running. Powertrain Control Module (PCM) determines that intake air flow amount is to low when intake air flow is less than .32 lbs/minute (2.4 grams/second) for 5 seconds and TP opening angle is more than 50 percent with engine running. PCM determines that intake air flow amount is to high when intake air flow amount is more than 10.6 lbs/minute (80 grams/second) for 5 seconds with engine speed less than 2000 RPM. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during first drive cycle. Possible causes are

  1. MAF sensor malfunction.
  2. Open or short circuit between PCM and MAF sensor.
  3. Open circuit between MAF sensor and ground.
  4. Throttle Position (TP) sensor malfunction.
  5. PCM malfunction.
  6. Open circuit between main relay and MAF sensor.

DTC is set when input voltage from MAP sensor is less than 0.2 volt or greater than 4.9 volts with engine running. Powertrain Control Module (PCM) determines that a MAP sensor performance problem is present when engine coolant temperature is more than 176°F (80°C) and differences between intake manifold vacuum and atmospheric pressure at idle is less than 1.9 in Hg. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during first drive cycle. Possible causes are

  1. MAP sensor malfunction.
  2. MAP sensor solenoid malfunction.
  3. Open or short circuit PCM and MAP sensor.
  4. PCM malfunction
  5. Loose, damaged, frozen or misrouted vacuum lines between MAP sensor and intake manifold.

Conditions

DTC is set if input voltage from IAT sensor (located in air cleaner) is less than 0.1 volt or greater than 4.8 volts when intake air temperature is 104° F (40° C) greater than engine coolant temperature with ignition on. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during first drive cycle. Possible causes are

  1. Air cleaner IAT sensor malfunction.
  2. Open or short circuit between IAT sensor (located in air cleaner) and Powertrain Control Module (PCM).
  3. Short between IAT sensor (located in air cleaner) circuits.
  4. PCM malfunction.

DTC is set if input voltage from ECT sensor is less than .2 volt or greater than 4.9 volts. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during first drive cycle. Possible causes are

  1. ECT sensor malfunction.
  2. Short circuit between PCM and instrument cluster.
  3. Open or short circuit between ECT sensor and PCM.
  4. PCM malfunction.

DTC is set when input voltage from TP sensor is less than .1 volt or greater than 4.8 volts after engine is started. Powertrain Control Module (PCM) determines that TP sensor is stuck closed if it detects throttle valve voltage is 0.6 volt for 5 seconds when engine coolant temperature is more than 176°F (80°C) and MAF sensor signal is more than 19.8 lbs/minute (150 grams/second). PCM determines that TP sensor is stuck open if it detects throttle valve voltage is 2.5 volts for 5 seconds when engine speed is more than 500 RPM and MAF sensor signal is less than .3 lbs/minute (2.4 grams/second). This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. TP sensor malfunction.
  2. Open or short circuit between PCM and TP sensor.
  3. PCM malfunction.
  4. Mass Airflow (MAF) sensor malfunction.

DTC is set when engine coolant temperature has not increased after engine is started cold and default period of time has passed with closed loop position switch in OFF position. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Engine Coolant Temperature (ECT) sensor malfunction.
  2. Poor circuit connector.
  3. PCM malfunction.

DTC is set when right front HO2S inversion cycle period (lean-to-rich and rich-to-lean response time) exceed specifications. Powertrain Control Module (PCM) checks right front HO2S operation during HO2S/TWC monitor repair verification drive mode. See HO2S/TWC MONITOR REPAIR VERIFICATION DRIVE MODE under DRIVE MODES. This happens when calculated engine load is 20-70 percent (depending on engine speed), engine speed is 1250-3000 RPM, vehicle speed is more than 2.2 MPH and engine coolant temperature is more than 14°F (-10°C). See HO2S/TWC MONITOR REPAIR VERIFICATION DRIVE MODE under DRIVE MODES. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are: .

  1. Right Front HO2S.
  2. Pressure Regulator Control (PRC) solenoid valve malfunction.
  3. Pressure regulator malfunction.
  4. Fuel pump Malfunction.
  5. Fuel filter plugged.
  6. Fuel leak at fuel line located at fuel rail and fuel pump.
  7. Exhaust system leak.
  8. Purge solenoid valve malfunction.
  9. Poor connection of purge solenoid hoses.
  10. Low engine compression.
  11. Engine malfunction.

DTC is set when right front HO2S signal voltage does not exceed .55 volt for 99 seconds during HO2S/TWC monitor repair verification drive mode, when engine speed is more than 1500 RPM and engine coolant temperature is more than 140°F (60°C). See HO2S/TWC MONITOR REPAIR VERIFICATION DRIVE MODE under DRIVE MODES. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Right front HO2S.
  2. Exhaust system leak.
  3. Open or short between right front HO2S and PCM.
  4. Low engine compression.
  5. Engine malfunction.

DTC is set when Powertrain Control Module (PCM) turns right front HO2S heater off, right front HO2S heater voltage input remains low, or when PCM turns right front HO2S heater on, right front HO2S heater voltage input remains high. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Right front HO2S.
  2. Open or short circuit between right front HO2S and PCM.
  3. Open circuit between right front HO2S and main relay.
  4. PCM malfunction.

DTC is set when right rear HO2S voltage is more than .45 volt for 6 seconds when vehicle is decelerating (fuel cut). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Right rear HO2S malfunction.
  2. Short circuit between right rear HO2S and PCM.

DTC is set when right rear HO2S signal voltage does not exceed .55 volt for 98 seconds during HO2S/TWC monitor repair verification drive mode, when engine speed is more than 1500 RPM and engine coolant temperature is more than 140°F (60°C). See HO2S/TWC MONITOR REPAIR VERIFICATION DRIVE MODE under DRIVE MODES. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Right rear HO2S.
  2. Exhaust system leak.
  3. Open or short between right rear HO2S and PCM.
  4. Low engine compression.
  5. Engine malfunction.

DTC is set when Powertrain Control Module (PCM) turns right rear HO2S heater off, right rear HO2S heater voltage input remains low, or when PCM turns right rear HO2S heater on, right rear HO2S heater voltage input remains high. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Right rear HO2S.
  2. Open or short circuit between right rear HO2S and PCM.
  3. Open circuit between right front HO2S and main relay.
  4. PCM malfunction.

DTC is set when left front HO2S inversion cycle period (lean-to-rich and rich-to-lean response time) exceed specifications. Powertrain Control Module (PCM) checks left front HO2S operation during HO2S/TWC monitor repair verification drive mode. See HO2S/TWC MONITOR REPAIR VERIFICATION DRIVE MODE under DRIVE MODES. This happens when calculated engine load is 20-70 percent (depending on engine speed), engine speed is 1250-3000 RPM, vehicle speed is more than 2.2 MPH and engine coolant temperature is more than 14°F (-10°C). This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Left Front HO2S.
  2. Pressure Regulator Control (PRC) solenoid valve malfunction.
  3. Pressure regulator malfunction.
  4. Fuel pump Malfunction.
  5. Fuel filter plugged.
  6. Fuel leak at fuel line located at fuel rail and fuel pump.
  7. Exhaust system leak.
  8. Purge solenoid valve malfunction.
  9. Poor connection of purge solenoid hoses.
  10. Low engine compression.
  11. Engine malfunction.

DTC is set when left front HO2S signal voltage does not exceed .55 volt for 99 seconds during HO2S/TWC monitor repair verification drive mode, when engine speed is more than 1500 RPM and engine coolant temperature is more than 140°F (60°C). See HO2S/TWC MONITOR REPAIR VERIFICATION DRIVE MODE under DRIVE MODES. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Left front HO2S.
  2. Exhaust system leak.
  3. Open or short between left front HO2S and PCM.
  4. Low engine compression.
  5. Engine malfunction.

DTC is set when Powertrain Control Module (PCM) turns left front HO2S heater off, left front HO2S heater voltage input remains low, or when PCM turns left front HO2S heater on, left front HO2S heater voltage input remains high. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Left front HO2S.
  2. Open or short circuit between left front HO2S and PCM.
  3. Open circuit between left front HO2S and main relay.
  4. PCM malfunction.

DTC is set when left rear HO2S voltage is more than .45 volt for 6 seconds when vehicle is decelerating (fuel cut). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Left rear HO2S malfunction.
  2. Short circuit between left rear HO2S and PCM.

DTC is set when left rear HO2S signal voltage does not exceed .55 volt for 98 seconds during HO2S/TWC monitor repair verification drive mode, when engine speed is more than 1500 RPM and engine coolant temperature is more than 140°F (60°C). See HO2S/TWC MONITOR REPAIR VERIFICATION DRIVE MODE under DRIVE MODES. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Left rear HO2S.
  2. Exhaust system leak.
  3. Open or short between left rear HO2S and PCM.
  4. Low engine compression.
  5. Engine malfunction.

DTC is set when Powertrain Control Module (PCM) turns left rear HO2S heater off, left rear HO2S heater voltage input remains low, or when PCM turns left rear HO2S heater on, left rear HO2S heater voltage input remains high. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Left rear HO2S.
  2. Open or short circuit between left rear HO2S and PCM.
  3. Open circuit between left rear HO2S and main relay.
  4. PCM malfunction.

DTC is set when PCM adaptive memory drive mode is running, right bank fuel injection closed loop correction and learning correction are greater than specified value because of system malfunction. See PCM ADAPTIVE MEMORY DRIVE MODE under DRIVE MODES. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Misfire.
  2. Right front HO2S malfunction.
  3. Pressure Regulator Control (PRC) solenoid malfunction.
  4. Fuel pressure regulator malfunction.
  5. Fuel pump malfunction.
  6. Fuel filter plugged.
  7. Fuel leak at fuel line located at fuel rail and fuel pump.
  8. Fuel return line plugged.
  9. Exhaust system leak.
  10. Purge solenoid valve malfunction.
  11. Poor connection of purge solenoid hoses.
  12. PCV valve malfunction.
  13. Low engine compression.

DTC is set when PCM adaptive memory drive mode is running, left bank fuel injection closed loop correction and learning correction are greater than specified value because of system malfunction. See PCM ADAPTIVE MEMORY DRIVE MODE under DRIVE MODES. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Misfire.
  2. Left front HO2S malfunction.
  3. Pressure Regulator Control (PRC) solenoid malfunction.
  4. Fuel pressure regulator malfunction.
  5. Fuel pump malfunction.
  6. Fuel filter plugged.
  7. Fuel leak at fuel line located at fuel rail and fuel pump.
  8. Fuel return line plugged.
  9. Exhaust system leak.
  10. Purge solenoid valve malfunction.
  11. Poor connection of purge solenoid hoses.
  12. PCV valve malfunction.
  13. Low engine compression.

Powertrain Control Module (PCM) monitors Crankshaft Position (CKP) sensor input signal interval time. It detects a misfire in a specific cylinder by calculating change of CKP interval time for each cylinder. While engine is operating, PCM counts number of misfires that occurred during 200 crankshaft revolutions and during 1000 crankshaft revolutions in order to calculate a misfire ratio for each crankshaft revolution. If misfire ratio exceeds a preprogrammed criteria, PCM determines that a misfire has occurred which can damage the catalytic converter and will set a DTC. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. CKP sensor malfunction.
  2. Camshaft Position (CMP) sensor malfunction.
  3. Ignition coil malfunction.
  4. Secondary ignition system malfunction.
  5. Mass Airflow (MAF) sensor malfunction.
  6. Vacuum leak between MAF sensor and plenum chamber.
  7. Fuel pump malfunction.
  8. Fuel pressure regulator malfunction.
  9. Plugged fuel line.
  10. Plugged fuel filter.
  11. Fuel lines leaking.
  12. Purge solenoid valve malfunction.
  13. PCV valve malfunction.
  14. EGR system malfunction.
  15. Vacuum hoses damaged or improperly connected.
  16. Poor connector connection or wiring problems.

Powertrain Control Module (PCM) monitors Crankshaft Position (CKP) sensor input signal interval time. It detects a misfire in a specific cylinder by calculating change of CKP interval time for each cylinder. While engine is operating, PCM counts number of misfires that occurred during 200 crankshaft revolutions and during 1000 crankshaft revolutions in order to calculate a misfire ratio for each crankshaft revolution. If misfire ratio exceeds a preprogrammed criteria, PCM determines that a misfire has occurred which can damage the catalytic converter and will set a DTC. DTC P0301 is set when cylinder No. 1 misfire is detected. DTC P0302 is set when cylinder No. 2 misfire is detected. DTC P0303 is set when cylinder No. 3 misfire is detected. DTC P0304 is set when cylinder No. 4 misfire is detected. DTC P0305 is set when cylinder No. 5 misfire is detected. DTC P0306 is set when cylinder No. 6 misfire is detected. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Spark plug malfunction.
  2. Secondary ignition system malfunction.
  3. Fuel injector malfunction.
  4. Vacuum leak between plenum chamber and cylinder head.
  5. Low engine compression.
  6. Poor connector connection or wiring problems.

DTC is set when input voltage of KS is less than 1.25 volts or greater than 3.75 volts when ignition is turned on. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during first drive cycle. Possible causes are

  1. KS malfunction.
  2. Open or short circuit between KS and PCM.
  3. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) does not receive input voltage from Crankshaft Position Sensor (CPS) for 1.4 seconds with engine cranking. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during first drive cycle. Possible causes are

  1. CKP sensor malfunction.
  2. CKP sensor dirty.
  3. Open or short circuit between CKP sensor and PCM.
  4. CKP sensor reluctor wheel malfunction.
  5. Starter switch malfunction.

DTC is set when difference in intake manifold pressure, with EGR on and EGR off, is too small. This is an intermittent monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. EGR valve malfunction.
  2. Manifold Absolute Pressure (MAP) sensor malfunction.
  3. MAP sensor solenoid valve malfunction.
  4. EGR gasket damage.
  5. EGR vacuum solenoid valve malfunction.
  6. EGR vent solenoid valve malfunction.
  7. PCM malfunction.

DTC is set if EGR valve does not achieve target position during EGR solenoid valve operation when engine speed is 1810-2190 RPM, throttle opening angle is 3-13.4 degrees, engine load is 25-50 percent and intake air temperature is more than 14°F (-10°C). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. EGR valve malfunction.
  2. EGR vacuum solenoid valve malfunction.
  3. EGR vent solenoid valve malfunction.
  4. Damaged, disconnected or misrouted vacuum hoses.
  5. PCM malfunction.

DTC is set when suspect side of front HO2S value difference becomes closer to value of suspect side of rear HO2S. This is monitored when engine speed is 1250-2094 RPM, vehicle speed is 22.9-74.8 MPH and vehicle is under 20-50 percent load. DTC P0421 is set when right bank catalyst system efficiency is below threshold. DTC P0431 is set when left bank catalyst system efficiency is below threshold. This is an intermittent monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Catalyst deterioration or malfunction.
  2. Exhaust leak.
  3. Loose HO2S.
  4. Left or right front HO2S malfunction.

Powertrain Control Module (PCM) checks for small EVAP system leaks by calculating the difference between two fuel tank pressure sensor readings. The first fuel tank pressure sensor reading is taken when both purge solenoid valve and Canister Drain Cut Valve (CDCV) are closed. This measurement will indicate a compensation gradient (amount of pressure created by expanding fuel vapor). The second fuel tank pressure sensor reading is taken after maximum EVAP system vacuum is reached, purge solenoid valve is closed and a preset period of time has elapsed. DTC is set when PCM detects excessive difference in fuel tank pressures measured after purge solenoid valve is closed with CDCV closed and preset period of time has elapsed. DTC is set during the following monitoring conditions

  1. Difference in fuel tank pressure between first and seconds reading is -.78 in. Hg. (-2.65 kPa). Difference is calculated by subtracting first reading from second reading.
  2. 15-85 percent or fuel remaining.
  3. Intake air temperature is more than 14°F (-10°C) when engine is first started.
  4. Engine coolant temperature 14-90.5°F (-10-32.5°C) when engine is first started.
  5. Atmospheric pressure is more than 21.3 in. Hg. (72 kPa).
  6. Vehicle speed is 25-65.3 MPH.
  7. Engine speed is 1000-3000 RPM.
  8. Calculated engine load is 9-70 percent.
  9. Throttle opening angle is 3-44 percent.
  10. Intake air temperature during monitoring is 14-140°F (-10-60°C).

This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Purge solenoid valve malfunction.
  2. CDCV malfunction.
  3. Pressure control valve malfunction.
  4. Loose fuel filler cap.
  5. Charcoal canister malfunction.
  6. Catch tank malfunction.
  7. Rollover valve malfunction.
  8. Cracked fuel tank.
  9. Poorly installed fuel tank components.
  10. Damaged or loose EVAP hose.

DTC is set when Powertrain Control Module (PCM) detects input signal from that purge solenoid valve is low after ignition is turned on. Possible causes are

  1. Purge solenoid valve malfunction.
  2. Open circuit between purge solenoid valve and main relay.
  3. Open or short circuit between purge solenoid valve and PCM.
  4. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) detects Fuel Tank Pressure (FTP) sensor input is less than .2 volt or greater than 4.8 volts with engine started and engine coolant temperature less than 176°F (80°C). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. FTP sensor malfunction.
  2. Open or short circuit between FTP sensor and PCM.
  3. PCM malfunction.

DTC is set when difference in fuel tank pressure is too high or too low for several seconds. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Fuel Tank Pressure (FTP) sensor malfunction.
  2. Purge solenoid valve malfunction.
  3. Canister Drain Cut Valve (CDCV) malfunction.
  4. Poor connection at CDCV, fuel tank pressure sensor and PCM connectors.
  5. Plugged charcoal canister.

Powertrain Control Module (PCM) checks for small EVAP system leaks by calculating the difference between two fuel tank pressure sensor readings. The first fuel tank pressure sensor reading is taken when both purge solenoid valve and Canister Drain Cut Valve (CDCV) are closed. This measurement will indicate a compensation gradient (amount of pressure created by expanding fuel vapor). The second fuel tank pressure sensor reading is taken after maximum EVAP system vacuum is reached, purge solenoid valve is closed and a preset period of time has elapsed. DTC is set when PCM detects excessive difference in fuel tank pressures measured after purge solenoid valve is closed with CDCV closed and preset period of time has elapsed. DTC is set during the following monitoring conditions

  1. Difference in fuel tank pressure between first and seconds reading is -.78 in. Hg. Difference is calculated by subtracting first reading from second reading.
  2. 15-85 percent fuel remaining.
  3. Intake air temperature is more than 14°F (-10°C) when engine is first started.
  4. Engine coolant temperature 14-90.5°F (-10-32.5°C) when engine is first started.
  5. Atmospheric pressure is more than 21.3 in. Hg. (72 kPa).
  6. Vehicle speed is 25-65.3 MPH.
  7. Engine speed is 1000-3000 RPM.
  8. Calculated engine load is 9-70 percent.
  9. Throttle opening angle is 3-44 percent.
  10. Intake air temperature during monitoring is 14-140°F (-10-60°C).

This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Purge solenoid valve malfunction.
  2. CDCV malfunction.
  3. Pressure control valve malfunction.
  4. Loose fuel filler cap.
  5. Charcoal canister malfunction.
  6. Catch tank malfunction.
  7. Check valve malfunction.
  8. Rollover valve malfunction.
  9. Cracked fuel tank.
  10. Poorly installed fuel tank components.
  11. Damaged or loose EVAP hose.
  12. Fuel tank pressure sensor malfunction.

DTC is set when fuel gauge sending unit input voltage to PCM does not level out to within 1 volt in 14 seconds with vehicle stopped and engine running. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible cause is: Fuel gauge sending unit malfunction.

DTC is set when condenser fan relay No. 1 coil control circuit input voltage is to low or to high. This is a continuous monitor. MIL will not illuminate. DTC is set when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Condenser fan relay No. 1 malfunction.
  2. Open or short circuit between condenser fan relay No. 1 and PCM.
  3. PCM malfunction.

DTC is set when cooling fan relay No. 1 or condenser fan relay No. 2 coil control circuit input voltage is to low or to high with ignition on. This is a continuous monitor. MIL will not illuminate. DTC is set when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Cooling fan relay No. 1 malfunction.
  2. Condenser fan relay No. 2 malfunction.
  3. Open or short circuit between cooling fan relay and PCM.
  4. Open or short circuit between condenser fan relay No. 2 and PCM.
  5. PCM malfunction.

DTC is set when cooling fan relay No. 2 and No. 3 coil control circuit input voltage is to low or to high with ignition on. This is a continuous monitor. MIL will not illuminate. DTC is set when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Cooling fan relay No. 2 malfunction.
  2. Cooling fan relay No. 3 malfunction.
  3. Open or short circuit between cooling fan relay No. 2 and PCM.
  4. Open or short circuit between cooling fan relay No. 3 and PCM.
  5. PCM malfunction.

DTC is set when there is no vehicle speed signal input to Powertrain Control Module (PCM) for 33 seconds or more. This is monitored when engine speed is more than 1810 RPM, charging efficiency is more than predetermined value and transmission is in Drive, Second or Low. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. PCM malfunction.
  2. Instrument cluster malfunction.
  3. Anti-lock Brake System (ABS)/Traction Control System (TCM) ABS hydraulic unit (HU)/Control Module (CM) malfunction.
  4. Open or short circuit between in-line 21-pin connector X17 and PCM.
  5. Open or short circuit between in-line 21-pin connector and instrument cluster.
  6. Open or short circuit between ABS/TCS HU/CM and instrument cluster.

Note. If atmospheric pressure is less than 21.3 in Hg or intake air temperature is less than 14°F (-10°C), PCM will cancel DTC P0505.

DTC is set when actual engine speed is less than target speed by 100 RPM or greater than target speed by 200 RPM for 14 seconds with engine coolant temperature at 140°F (60°C), brake pedal depressed (brake switch on), and steering wheel in straight ahead position (power steering pressure switch off). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Idle Air Control (IAC) valve malfunction.
  2. Open or short circuit between IAC and main relay.
  3. Open or short circuit between IAC and PCM.
  4. PCM malfunction.
  5. Misadjusted accelerator cable.
  6. Misadjusted cruise control cable.
  7. Throttle valve malfunction.
  8. Improperly connected vacuum hoses.
  9. Plugged air filter.
  10. Plugged intake passage.
  11. A/C relay malfunction.
  12. Generator circuit malfunction.
  13. Purge solenoid valve malfunction.
  14. Low engine compression.

DTC is set when Powertrain Control Module (PCM) has not received a voltage signal from CTP switch while vehicle is driven at speeds more than 18 MPH and stopped 10 times repeatedly. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. CTP switch malfunction.
  2. Open or short circuit between TP sensor and PCM.
  3. PCM malfunction.

DTC is set if Powertrain Control Module (PCM) receives a low power steering switch signal continuously for more than 60 seconds when vehicle speed is 37 MPH or more and coolant temperature is 140°F (60°C) or more. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Power Steering Pressure (PSP) switch malfunction.
  2. Short circuit between PSP switch and PCM.
  3. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) has not received a voltage change from brake switch when brake pedal is activated 10 times and vehicle speed is 18 MPH or more. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Brake switch malfunction.
  2. Open circuit between brake switch and PCM.
  3. PCM malfunction.

DTC is set when input voltage from Intake Air Temperature (IAT) sensor mounted in air intake resonator is less than 0.1 volt or more than 4.9 volts when intake air temperature is more than 14°F (-10°C), engine coolant temperature is more than 158°F (70°C) and intake air temperature is more than engine coolant temperature by 104°F (40°C). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during first drive cycle. Possible causes are

  1. Air intake resonator IAT sensor malfunction.
  2. Open or short circuit between IAT sensor and PCM.
  3. PCM malfunction.

DTC is set when input voltage from Intake Air Temperature (IAT) sensor mounted in Lysholm Compressor (L/C) is greater than 4.9 volts when intake air temperature is greater than 32°F (0°C). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during first drive cycle. Possible causes are

  1. L/C IAT sensor malfunction.
  2. Open or short circuit between L/C IAT sensor and PCM.
  3. PCM malfunction.

DTC is set when right front HO2S signal voltage is more than or less than .45 volt and remains unchanged for 32 seconds with engine speed more than 1500 RPM and engine coolant temperature more than 176°F (80°C). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Right front HO2S.
  2. Fuel injector malfunction.
  3. Fuel pressure regulator malfunction.
  4. Fuel pump malfunction.
  5. Fuel delivery or return hose plugged or leaking.
  6. Fuel filter plugged.
  7. Vacuum leak.
  8. PCV valve malfunction.
  9. Purge solenoid valve malfunction.
  10. Purge solenoid hoses improperly installed.
  11. Ignition coil malfunction.
  12. Low engine compression.
  13. Engine malfunction.

DTC is set when left front HO2S signal voltage is more than or less than .45 volt and remains unchanged for 32 seconds with engine speed more than 1500 RPM and engine coolant temperature more than 176°F (80°C). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Left front HO2S.
  2. Fuel injector malfunction.
  3. Fuel pressure regulator malfunction.
  4. Fuel pump malfunction.
  5. Fuel delivery or return hose plugged or leaking.
  6. Fuel filter plugged.
  7. Vacuum leak.
  8. PCV valve malfunction.
  9. Purge solenoid valve malfunction.
  10. Purge solenoid hoses improperly installed.
  11. Ignition coil malfunction.
  12. Low engine compression.
  13. Engine malfunction.

DTC is set when input signal from starter to Powertrain Control Module (PCM) continues for more than 20 seconds with engine speed greater than 2000 RPM. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Starter malfunction.
  2. Short circuit between starter and PCM.
  3. Short circuit between starter relay and PCM.
  4. Starter relay stuck closed.
  5. PCM malfunction.

DTC is set when input signal from PRC solenoid valve to Powertrain Control Module (PCM) is low when ignition is on. This circuit is monitored once per ignition cycle. MIL will not illuminate. Possible causes are

  1. PRC solenoid valve malfunction.
  2. Open or short circuit between PRC solenoid valve and PCM.
  3. Open circuit between PRC solenoid valve and main relay.
  4. PCM malfunction.

DTC is set when there is no signal input from Camshaft Position (CMP) sensor after crankshaft pulley has rotated 4.5 times. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during first drive cycle. Possible causes are

  1. CMP sensor malfunction.
  2. Open or short circuit between CMP sensor and PCM.
  3. Open or short circuit between PCM and main relay.
  4. PCM malfunction.

DTC is set when input voltage from EGR valve position sensor is less than .2 volt or greater than 4.7 volts. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during first drive cycle. Possible causes are

  1. EGR valve position sensor malfunction.
  2. Open or short circuit between Powertrain Control Module (PCM) and EGR valve position sensor.
  3. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) detects input voltage from CDCV system is low with ignition switch on. This circuit is monitored once per ignition cycle. MIL will not illuminate. Possible causes are

  1. CDCV malfunction.
  2. Open or short circuit between CDCV and PCM.
  3. Open circuit between CDCV and main relay.
  4. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) detects fuel tank pressure is more than 1.45 in Hg (-4.9 kPa) for 8 seconds when intake air temperature is more than 14°F (-10°C), engine coolant temperature is 216°F (102°C) or less, vehicle speed is 59 MPH or less and engine coolant temperature when engine is first started is 95°F (35°C). This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Canister Drain Cut Valve (CDCV) malfunction.
  2. CDCV air filter plugged.
  3. Charcoal canister malfunction.
  4. Clogs or leakage in system vacuum hoses.
  5. 2-way check valve plugged.
  6. Fuel tank pressure sensor malfunction.
  7. Purge solenoid malfunction.

DTC is set if Powertrain Control Module (PCM) detects fuel gauge sending unit input voltage is 0.8 volt or more than 4.8 volts for 5 seconds. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. Fuel gauge malfunction.
  2. Fuel gauge sending unit malfunction.
  3. PCM malfunction.
  4. Open or short circuit between fuel gauge sending unit and PCM.
  5. Open or short circuit between fuel gauge sending unit and instrument cluster.
  6. Open circuit between fuel gauge sending unit and ground.

DTC is set when Powertrain Control Module (PCM) detects low MAP sensor solenoid valve system input voltage when ignition switch is on. This circuit is monitored once per ignition cycle. MIL will not illuminate. Possible causes are

  1. MAP sensor solenoid valve malfunction.
  2. Open or short circuit between MAP sensor solenoid valve and PCM.
  3. Open circuit between PCM and main relay.
  4. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) detects by-pass air solenoid valve voltage is more than 11.5 volts with by-pass air solenoid valve on or less than 5.8 volts with by-pass air solenoid valve off. This circuit is monitored once per ignition cycle. MIL will not illuminate. Possible causes are

  1. By-pass air solenoid valve malfunction.
  2. Open circuit between by-pass air solenoid valve and main relay.
  3. Open or short circuit between by-pass air solenoid valve and PCM.
  4. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) detects low charge air cooler by-pass solenoid valve voltage when ignition is on. This circuit is monitored once per ignition cycle. MIL will not illuminate. Possible causes are

  1. Charge air cooler by-pass solenoid valve malfunction.
  2. Open circuit between charge air cooler by-pass solenoid valve and main relay.
  3. Open or short circuit between charge air cooler by-pass solenoid valve and PCM.
  4. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) detects ABV solenoid valve (vacuum) voltage is more than 11.5 volts with ABV solenoid valve (vacuum) on or less than 5.8 volts with ABV solenoid valve (vacuum) off. This circuit is monitored once per ignition cycle. MIL will not illuminate. Possible causes are

  1. ABV solenoid valve (vacuum) malfunction.
  2. Open circuit between ABV solenoid valve (vacuum) and main relay.
  3. Open or short circuit between ABV solenoid valve (vacuum) and PCM.
  4. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) detects ABV solenoid valve (vent) voltage is more than 11.5 volts with ABV solenoid valve (vent) on or less than 5.8 volts with ABV solenoid valve (vent) off. This circuit is monitored once per ignition cycle. MIL will not illuminate. Possible causes are

  1. ABV solenoid valve (vent) malfunction.
  2. Open circuit between ABV solenoid valve (vent) and main relay.
  3. Open or short circuit between ABV solenoid valve (vent) and PCM.
  4. PCM malfunction.

DTC is set when difference between actual charge pressure and target charge pressure is greater than 5.8 in Hg. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are

  1. ABV actuator malfunction.
  2. ABV solenoid valve (vacuum) malfunction.
  3. ABV solenoid valve (vent) malfunction.
  4. Charge air cooler by-pass actuator stuck closed.
  5. Charge air cooler by-pass solenoid valve malfunction.
  6. Manifold Absolute Pressure (MAP) sensor malfunction.
  7. MAP sensor solenoid valve malfunction.
  8. Vacuum system leakage or blockage.
  9. Lysholm Compressor Intake Air Temperature (L/C IAT) sensor malfunction.
  10. Lysholm Compressor malfunction.
  11. PCM malfunction.

DTC is set when short or open is present in signal circuit between Transmission Control Module (TCM) to Powertrain Control Module (PCM). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during first drive cycle. Possible causes are

  1. Poor connector connection at PCM or TCM.
  2. Open or short circuit between PCM and TCM.
  3. TCM malfunction.
  4. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) reads out of range output device signals. Possible causes are

  1. Short to power on signal circuit.
  2. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) reads abnormal integrated knock control circuit signal. Possible causes are

  1. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) does not receive a pulse signal from ABS/TCS HU/CM at more than 3.3 MPH. Possible causes are

  1. ABS/TCS HU/CM malfunction.
  2. Open or short circuit between ABS/TCS HU/CM and PCM.
  3. PCM malfunction.

DTC is set when Powertrain Control Module (PCM) does not receive a pulse signal from ABS/TCS at more than 3.3 MPH. Possible causes are

  1. ABS/TCS malfunction.
  2. Open or short circuit between ABS/TCS and PCM.
  3. PCM malfunction.

DTC is set when backup battery voltage at Powertrain Control Module (PCM) is less than 1.4 volts when ignition is on or when engine is running. This is a continuous monitor. MIL will illuminate when Powertrain Control Module (PCM) detects malfunction during first drive cycle. Possible causes are

  1. Open ROOM fuse (15-amp).
  2. Open or short circuit between PCM and positive battery cable.
  3. PCM malfunction.

Incorrect reference voltage. Possible causes are

  1. EGR valve position sensor, reference voltage circuit malfunction.
  2. Fuel Tank Pressure (FTP) sensor, reference voltage circuit malfunction.
  3. Throttle Position (TP) sensor, reference voltage circuit malfunction.
  4. Transmission Control Module (TCM), reference voltage circuit malfunction.
  5. Manifold Absolute Pressure (MAP) sensor, reference voltage circuit malfunction.

More articles — Engine Controls - Self-Diagnostics - Millenia 2.3L