Engine Controls - Self-Diagnostics: Other Mazda MX-5 NB рестайлинг

Pending Codes

Pending codes appear when a problem is detected in a monitored system. Malfunction Indicator Light (MIL) is illuminated when a problem is detected in 2 consecutive drive cycles. 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).

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 (EPROM) card is inserted into NGS scan tool. Connect service connections of adapter cable to vehicle DLC-2 and NGS scan tool. see scheme 1 Connect NGS scan tool power supply cable to power and listen for a double beep to indicate that 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 PID DATA.
4. Select START and follow scan tool prompts.

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

Mode 1 - PCM Adaptive Memory Produce Drive Mode

1. Start engine and let it idle until reaches normal operating temperature.
2. Verify if vehicle is under following conditions, perform correction if necessary: All accessory loads (A/C, headlights, blower fan, rear window defroster) are off. Initial ignition timing and idle speed are within specification. For adjustments see «IDLE SPEED & IGNITION TIMING»(ref-151876-S29886790492003010800000) in ON-VEHICLE ADJUSTMENTS article. TEN and GND terminals of DLC-1 are not connected.
3. Race engine speed as shown in graph. (Scheme 43) Then idle engine for more than 20 seconds, after cooling fan has stopped. If possible, monitor RPM PID for engine speed and FAN1 PID (without A/C) or FAN2 PID (with A/C) for cooling fan status during this procedure.

Scheme 43

Mode 2 - EGR System Repair Verification Drive Mode

1. Perform Mode 1 first.
2. Verify all accessory loads (A/C, headlights, blower fan, rear window defroster) are off.
3. Ensure engine at normal operating temperature and drive vehicle as shown in graph. (Scheme 44)
4. Stop vehicle and access ON BOARD SYSTEM READINESS menu of GENERIC OBD-II FUNCTIONS to inspect Drive Mode completion status. If completed, Readiness Function Check (RFC) flag changes from NO to YES. If not completed, turn ignition off and repeat testing from step 3.
5. Access DIAGNOSTIC MONITORING TEST RESULTS menu of GENERIC OBD-II FUNCTIONS to inspect monitor results. If MEAS are within specification, repair is completed. If MEAS are not within specification, repair is not completed.
6. Verify no DTCs are available.

Scheme 44

Mode 3 - HO2S Heater, HO2S & TWC Repair Verification Drive Mode

1. Perform Mode 1 first.
2. Verify all accessory loads (A/C, headlights, blower fan, rear window defroster) are off.
3. Ensure engine is at normal operating temperature and drive vehicle as shown in graph. (Scheme 45) (Driving condition before driving vehicle at constant speed for more than 5 minutes is not specified).
4. Stop vehicle and access ON BOARD SYSTEM READINESS menu of GENERIC OBD-II FUNCTIONS to inspect completion status. If completed, Readiness Function Check (RFC) flag changes from NO to YES. If not completed, turn ignition off and repeat testing from step 3.
5. Access DIAGNOSTIC MONITORING TEST RESULTS menu of GENERIC OBD-II FUNCTIONS to inspect monitor results. If MEAS are within specification, repair is completed. If MEAS are not within specification, repair is not completed.
6. Verify no DTCs are available.

Scheme 45

Mode 4 - EVAP System Repair Verification Drive Mode

Note. If Mode 4 can not be performed because it is impossible to drive vehicle under Mode 4 conditions, perform evaporative system test procedure as an alternative. See FUEL EVAPORATIVE SYSTEM (MIATA & MPV) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article. Mode 4 can be performed regardless of RFCFLAG status.

1. Verify that all following PIDs are within specification before engine is started to initiate evaporative monitoring: Barometric pressure (BARO) is 21.3 IN. Hg (72 kPa). Fuel Tank Level (FTL) PID is.24-2.0 volts. Intake Air Temperature (IAT) is 14-140°F (-10-60°C). Engine Coolant Temperature (ECT) is 14-95°F (-10-35°C).
2. Verify all accessory loads (A/C, headlights, blower fan, rear window defroster) are off.
3. Start engine and race at 3500 RPM until it reaches normal operating temperature. Drive vehicle as shown in graph. (Scheme 46)
4. Stop vehicle and access ON BOARD SYSTEM READINESS menu of GENERIC OBD-II FUNCTIONS to inspect completion status. Test is complete when Readiness Function Check (RFC) flag changes from NO to YES. Go to next step. If test is not complete, turn ignition off and go back to step 3.
5. Access DIAGNOSTIC MONITORING TEST RESULTS menu of GENERIC OBD-II FUNCTIONS to inspect monitor results. If MEAS values of 10:21:00 and 10:22:00 are within specification, repair is completed. If MEAS values of 10:21:00 and 10:22:00 are not within specification, repair is not completed.
6. Verify no DTCs are available.

Scheme 46

SUMMARY

If no Diagnostic Trouble Codes (DTCs) are present and a no-start condition exists, proceed to BASIC DIAGNOSTIC PROCEDURES article. If no DTCs are present and a driveability condition exists, proceed to TROUBLESHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

Detection Condition

PCM monitors Oil Control Valve (OCV) and DTC is set if PCM detects OCV signal circuit current or control circuit current (calculated from OCV) is above and below threshold voltage (calculated from battery positive voltage), PCM determines that OCV circuits has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Therefore pending codes is not available. Freeze Frame Data is available and DTC will store in PCM memory.

Possible Causes

1. OCV circuit malfunction.
2. Open or short circuit between OCV and PCM.
3. PCM malfunction.
4. Poor connection at OCV or PCM harness connectors.

DTC is set when actual valve timing is over-advanced by 15 degrees from target valve timing when Oil Control Valve (OCV) system controls within maximum valve timing retard. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction conditions in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

1. Loose timing belt or improper valve timing due to jumping.
2. OCV malfunction.
3. OCV spool valve stuck in advance position.
4. PCM malfunction.
5. Variable valve timing actuator is stuck in advance position.

DTC is set when actual valve timing is over-retarded by 10 degrees from target valve timing for 5 seconds when Oil Control Valve (OCV) system control is within feed-back range. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

1. Loose timing belt or improper valve timing due to jumping of timing belt.
2. Low engine oil pressure.
3. OCV malfunction.
4. OCV spool valve stuck in retard position.
5. Oil runners are clogged or have leakage: Between OCV and variable valve timing actuator. Between oil pressure switch and OCV. In variable valve timing actuator.
6. PCM malfunction.
7. Variable valve timing actuator is stuck in retard position.

DTC is set when PCM detects low input voltage from ground side of front HO2S heater circuit after PCM turns HO2S heater circuit off. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction condition in 2 consecutive drive cycles. HO2S heater is controlled by a duty signal. Pending codes is available if PCM detects malfunction during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

1. Front HO2S malfunction.
2. Loose connection at front HO2S or PCM harness connectors.
3. Open or short circuit between front HO2S and PCM.
4. Open circuit between front HO2S and ignition switch.
5. PCM malfunction.

DTC is set when PCM detects high input voltage from ground side of front HO2S heater circuit after PCM turns HO2S heater circuit on. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction condition in 2 consecutive drive cycles. Pending codes is available if PCM detects malfunction during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

1. PCM malfunction.
2. Shorted front HO2S or PCM terminal.
3. Short to power between front HO2S and PCM.

DTC is set when PCM detects low input voltage from ground side of rear HO2S heater circuit after PCM turns HO2S heater circuit off. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction condition in 2 consecutive drive cycles. HO2S heater is controlled by a duty signal. Pending codes is available if PCM detects malfunction during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

1. Loose connection at connectors.
2. Open circuit between rear HO2S and fuse block (inside vehicle).
3. Open or short circuit between rear HO2S and PCM.
4. PCM malfunction.
5. Rear HO2S malfunction.

DTC is set when PCM detects high input voltage from ground side of rear HO2S heater circuit after PCM turns HO2S heater circuit on. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction condition in 2 consecutive drive cycles. Pending codes is available if PCM detects malfunction during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

1. PCM malfunction.
2. Rear HO2S malfunction.
3. Shorted rear HO2S or PCM terminal.
4. Short to power between rear HO2S and PCM.

DTC is set when PCM compares actual input signal from Mass Airflow (MAF) sensor with expected input signal from MAF sensor which PCM calculates by engine speed. If mass intake-airflow amount is more than 9.88 lb./min (74.7 grams/sec) for 5 seconds and engine speed is less than 2000 RPM with engine running, PCM determines that detected mass intake-airflow amount is too high. If mass intake-airflow amount is less than 0.70 lb/min (5.3 grams/sec) for 5 seconds and engine speed is more than 500 RPM with engine running, PCM determines that detected mass intake-airflow amount is too low. MIL is illuminated when PCM detects malfunction condition in 2 consecutive drive cycles. Pending codes is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

Monitoring Condition

1. ECT is more than 158°F (70°C).
2. Throttle opening angle is more than 50 percent.

1. Electrical corrosion in MAF return circuit.
2. MAF sensor malfunction.
3. Voltage drops in GND circuit.

PCM monitors input voltage from Mass Airflow (MAF) sensor after ignition is on. If input voltage at PCM terminal 4X is less than 0.86 volt, PCM determines that MAF circuit has a malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Therefore, pending code is not available. Freeze frame data is available and DTC will store in PCM memory.

1. Connectors or terminal malfunction.
2. MAF sensor malfunction.
3. Open circuit between main relay and MAF sensor.
4. Open or short between MAF sensor and PCM.
5. PCM malfunction.

PCM monitors input voltage from Mass Airflow (MAF) sensor after ignition is on. If input voltage at PCM terminal 4X is more than 4.9 volts, PCM determines that MAF circuit has a malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Therefore, pending code is not available. Freeze frame data is available and DTC will store in PCM memory.

1. Connector or terminal malfunction.
2. MAF sensor malfunction.
3. Open or short between MAF sensor and PCM.

PCM monitors barometric pressure by monitoring difference between intake manifold vacuum and atmospheric pressure at idle. PCM monitors atmospheric pressure at idle by using EGR boost sensor and by switching EGR boost sensor solenoid. DTC is set when barometric pressure variation is less than 1.8 in/Hg (6.4 kPa). This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

1. EGR boost sensor malfunction or substandard performance.
2. EGR boost sensor solenoid valve malfunction.
3. EGR boost sensor valve hose or pipe loose, plugged (frozen moisture in hose) or damaged.

PCM monitors input voltage from Exhaust Gas Recirculation (EGR) boost sensor when monitoring conditions are

Monitoring Conditions

1. Intake Air Temperature (IAT) is more than 50°F (10°C).
2. EGR boost sensor solenoid is turned off (BARO is applied to EGR boost sensor).

If input voltage at PCM terminal "4AE" is less than 0.21 volt, PCM determines that EGR boost sensor circuit is malfunctioning. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC will store in PCM memory.

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

PCM monitors voltage from EGR boost sensor when Intake Air Temperature (IAT) is more than 50°F (10°C) and EGR boost sensor solenoid is turned off (atmospheric pressure is applied to sensor). DTC is set when input voltage from EGR boost sensor is more than 4.8 volts. This is a Continuous Monitor (CM). MIL is illuminated when PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze frame data is available and DTC will store in PCM memory.

1. Connector or terminal malfunction.
2. EGR boost sensor malfunction.
3. EGR boost sensor signal circuit short to reference voltage supply circuit.
4. Open or short circuit between EGR boost sensor and PCM.
5. PCM malfunction.

DTC is set if input voltage from Intake Air Temperature (IAT) sensor indicates 104°F (40°C) greater than input from Engine Coolant Temperature (ECT) sensor. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is available, if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

1. IAT sensor malfunction.
2. Poor connection at IAT sensor and PCM harness connectors.
3. PCM malfunction.

DTC is set if input voltage from Intake Air Temperature (IAT) is less than .2 volt. This is a Continuous Monitor (CM). MIL is illuminated when PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC will store in PCM memory.

1. IAT sensor malfunction.
2. IAT signal and IAT GND circuits shorted to each other.
3. PCM malfunction.
4. Short circuit between IAT sensor and PCM harness connectors.

PCM monitors Intake Air Temperature (IAT) sensor signal at PCM terminal "4N". If voltage at PCM terminal "4N" is less than 0.2 volt, PCM determines that IAT sensor circuit has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

1. IAT sensor malfunction.
2. Open or short circuit between IAT sensor and PCM.
3. Poor connection at IAT sensor and PCM connectors.
4. PCM malfunction.

DTC is set if difference between maximum and minimum input value of ECT is less than 10.1°F (5.6°C). Difference is measured after allowing vehicle to be off for at least 6 hours and starting vehicle and allowing it to idle for 5 minutes. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycle. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC will store in PCM memory.

1. ECT sensor malfunction.
2. Poor connection at ECT sensor or PCM harness connectors.
3. PCM malfunction.

PCM monitors ECT sensor signal at PCM terminal "4P". If voltage at terminal "4P" is less than 0.20 volt. PCM determines that ECT sensor circuit has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

1. ECT sensor malfunction.
2. ECT signal and GND circuit short to each other.
3. PCM malfunction.
4. Short to ground between ECT sensor and PCM harness connectors.

PCM monitors ECT sensor signal at PCM terminal "4P". If voltage at terminal "4P" is more than 4.94 volts, PCM determines that ECT sensor circuit has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

1. ECT sensor malfunction.
2. Open or short circuit between ECT sensor and PCM.
3. PCM malfunction.
4. Poor ECT sensor and PCM connection.

DTC is set if PCM detects throttle valve opening angle is less than 12.5 percent for 5 seconds after following conditions are met. PCM determines TP sensor is stuck closed.

Monitoring Conditions

1. ECT is more than 158°F (70°C).
2. MAF sensor signal is more than 8.36 lb/min (63.2 grams/sec).

DTC is also set if PCM detects throttle valve opening angle is more than 50 percent for 5 seconds after following conditions are met. PCM determines that TP is stuck open.

Monitoring Conditions

1. Engine speed is more than 500 RPM.
2. MAF sensor signal is less than 0.7 lb/min (5.3 grams/sec).

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction conditions in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. PCM malfunction.
2. TP sensor connector malfunction.
3. TP sensor malfunction.
4. Voltage drop in reference voltage (Vref) supply circuit.

DTC is set when PCM detects TP sensor voltage at PCM 31-pin harness connector terminal "4V" is less than 0.1 volt after engine start. PCM determines TP circuit has a malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Connector or terminal malfunction.
2. Open or short circuit between PCM and TP sensor.
3. PCM malfunction.
4. TP sensor malfunction.

DTC is set when PCM detects TP sensor voltage at PCM 31-pin harness connector terminal "4V" is more than 4.8 volts after engine start. PCM determines that TP circuit has a malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction conditions in 2 consecutive drive cycles. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

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

PCM monitors Engine Coolant Temperature (ECT) sensor signal at PCM terminal "4P" after engine is started when engine is cold. If ECT voltage does not reach expected temperature within specified period. DTC is set when PCM determines that it has taken an excessive amount of time for ECT to reach necessary temperature to start closed-loop fuel control. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. ECT sensor malfunction.
2. Poor connection of connectors.
3. PCM malfunction.

DTC is set if Engine Coolant Temperature (ECT) signal never exceeds 160°F (71°C), after engine is been running for specified period of time under following monitoring conditions. PCM determines that coolant thermostat is stuck open.

Monitoring Conditions

1. Intake Air Temperature (IAT) is more than 14°F (-10°C).
2. Difference between ECT at engine start and minimum IAT is less than 10.8°F (6°C).
3. Vehicle speed is over 5.9 MPH.

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Coolant thermostat malfunction.
2. Engine cooling fan malfunction.
3. ECT sensor malfunction.
4. PCM malfunction.

DTC is set when PCM monitors input voltage from front HO2S when following monitoring conditions are met, PCM determines that there is no front HO2S inversion

Monitoring Conditions

1. Voltage from front HO2S remains less than 0.45 volt for 43.3 seconds.
2. Engine speed is more than 1500 RPM.
3. Engine coolant temperature is more than 158°F (70°C).

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle and Freeze Frame Data is available.

1. Front HO2S malfunction.
2. Front HO2S heater malfunction.
3. Fuel injector malfunction.
4. Fuel pressure regulator malfunction.
5. Fuel pump malfunction.
6. Fuel filter clogged.
7. Fuel delivery and return line leakage.
8. Positive Crankcase Ventilation (PCV) valve malfunction.
9. Purge Control Solenoid Valve (PCSV) and hoses malfunction.
10. Ignition malfunction.
11. Low engine compression.
12. Engine malfunction.

PCM monitors input voltage from front Heated Oxygen Sensor (HO2S) when the following monitoring conditions are met, PCM determines that there is no front HO2S inversion

Monitoring Conditions

1. If input voltage from sensor remains more than 0.45 volt for 43.3 seconds.
2. Engine speed is more than 1500 RPM.
3. Engine coolant temperature is more than 158°F (70°C).

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle and Freeze Frame Data is available.

1. Engine malfunction.
2. FrontHO2S heater malfunction.
3. FrontHO2S malfunction.
4. Fuel injector malfunction.
5. Fuel pressure regulator malfunction.
6. Fuel pump malfunction.
7. Fuel return hose clogged.
8. PCV valve malfunction.
9. Purge solenoid valve hoses installed incorrectly.
10. Purge solenoid valve malfunction.

PCM monitors inversion cycle period, lean-to-rich response time and rich-to-lean response time of frontHO2S. PCM calculates average of inversion cycle period-specified inversion cycles, average response time from lean-to-rich; and rich-to-lean. If any exceeds threshold, PCM determines that circuit has malfunction when drive mode 3 and following conditions are met

Monitoring Conditions

1. Calculation load is 16-50 percent (MT), 20-50 percent (AT) at 2000 RPM.
2. Engine speed is 750-3100 RPM (MT), 810-3100 RPM (AT).
3. Vehicle speed is more than 3.5 MPH.
4. Engine coolant temperature is more than 14°F (-10°C).

This is an intermittent monitor. MIL illuminates if PCM detects either malfunction condition in 2 consecutive drive cycles. Diagnostic monitoring test results is available. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Engine malfunction.
2. FrontHO2S deterioration.
3. FrontHO2S heater malfunction.
4. Fuel filter clogged or restricted.
5. Fuel leakage on fuel line from fuel distribution pipe and fuel pump.
6. Fuel pump malfunction.
7. Fuel return hose clogged.
8. Insufficient engine compression.
9. Leakage from exhaust system.
10. Pressure Regulator Control (PRC) solenoid valve.
11. Pressure regulator malfunction.
12. Purge solenoid valve hoses installed incorrectly.
13. Purge solenoid valve malfunction.

DTC is set when PCM monitors input voltage from front Heated Oxygen Sensor (HO2S). If input voltage from front HO2Snever exceeds 0.55 volt for 54.2 seconds, PCM determines that sensor circuit is not activated when following conditions are met

Monitoring Conditions

1. Drive mode 3.
2. Engine speed is more than 1500 RPM.
3. ECT is more than 158°F (70°C).

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Engine malfunction.
2. Front HO2S deterioration.
3. Front HO2S heater malfunction.
4. Leakage exhaust system.
5. Low engine compression.
6. Open or short to ground circuit between front HO2S and PCM harness connector terminals.

DTC is set when rear HO2S voltage is more than .45 volt for 6 seconds when vehicle is decelerating (fuel cut). PCM determines that circuit input is high.

1. Rear HO2S malfunction.
2. Short circuit between rear HO2S and PCM.

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

PCM monitors input voltage from rear Heated Oxygen Sensor (HO2S). If input voltage from rear HO2Snever exceeds 0.55 volt for 54.2 seconds, PCM determines that sensor circuit is not activated when drive mode 3 and following conditions are met

Monitoring Condition

1. Engine speed is more than 1500 RPM.
2. ECT is more than 158°F (70°C).

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Engine malfunction.
2. Exhaust system leak.
3. Low engine compression.
4. Open or short to ground circuit between rear HO2S and PCM.
5. Rear HO2S deterioration.
6. Rear HO2S heater malfunction.

PCM monitors Short Term Fuel Trim (SHRTFT) and Long Term Fuel Trim (LONGFT) values when monitoring conditions are met or DRIVE MODE 1 is run. If fuel trim exceeds preprogrammed criteria, PCM determines that the fuel system is too lean. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction conditions during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Exhaust system leak.
2. Fuel filter clogged or restricted.
3. Front HO2S malfunction.
4. Front HO2S heater malfunction.
5. Fuel lines or fuel pump leaking.
6. Fuel pressure regulator malfunction.
7. Fuel pump malfunction.
8. Low compression.
9. Misfire.

PCM monitors Short Term Fuel Trim (SHRTFT) and Long Term Fuel Trim (LONGFT) values when monitoring conditions are met or DRIVE MODE 1 is run. If fuel trim exceeds preprogrammed criteria, PCM determines that fuel system is too rich. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Front HO2S heater malfunction.
2. Front HO2S deterioration.
3. Fuel pressure regulator malfunction.
4. Fuel pump malfunction.
5. Misfire.
6. Purge Solenoid Valve hoses improperly connected.
7. Purge Solenoid Valve malfunction.

PCM monitors Crankshaft Position (CKP) sensor input signal interval time. PCM 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 occur 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 catalytic converter or affect emission performance and will set a DTC. This is a Continuous Monitor (CM). MIL illuminates if PCM detects misfire which affects emission performance in 2 consecutive drive cycles. Pending code is available if PCM detects misfire which affects emission performance. MIL flashes if PCM detects misfire which can damage catalytic converter during first drive cycle. Therefore, pending code is not available while MIL flashes. Freeze Frame Data is available and DTC is stored in PCM memory.

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

PCM monitors Crankshaft Position (CKP) sensor input signal interval time. PCM 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 occur 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. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction conditions during first drive cycle. MIL flashes if PCM detects misfire which can damage catalytic converter during first drive cycle. Therefore, pending code is not available while MIL flashes. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Fuel injector malfunction.
2. Low engine compression.
3. Poor connector or terminal malfunction.
4. Related wiring harness malfunction.
5. Secondary ignition system malfunction.
6. Spark plug malfunction.
7. Vacuum leak in intake-air system between dynamic chamber and cylinder head.

DTC is set when PCM detects input voltage from Knock Sensor (KS) is less than 1.25 volts after ignition is turned on. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Connector or terminal malfunction.
2. KS malfunction.
3. Short to ground circuit between KSand PCM.

DTC is set when PCM detectsinput voltage from Knock Sensor (KS) is more than 3.75 volts after ignition is turned on. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

Possible Condition

1. Connectors and terminals malfunction.
2. KS malfunction.
3. Open circuit between KS and PCM.

DTC is set when there is no signal input from Crankshaft Position (CKP) sensor for 4.2 seconds while Mass Airflow (MAF) sensor output voltage is 2.0-4.9 volts. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

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

DTC is set when PCM does not receive input signal from Camshaft Position (CMP) sensor while receiving input signal from Crankshaft Position (CKP) sensor and Mass Airflow (MAF) is more than 2.7 grams/sec. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

1. CKP sensor malfunction.
2. CMP sensor malfunction or dirty.
3. Connector or terminal malfunction.
4. Open or short circuit between PCM and CMP sensor.
5. Open or short circuit between main relay and CMP sensor.

DTC is set when PCM detects difference in intake manifold pressure between open EGR and closed EGR is too small. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. DIAGNOSTIC MONITORING TEST RESULTS and PENDING CODE are available if PCM detects malfunction conditions during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. EGR boost sensor malfunction.
2. EGR boost sensor solenoid valve malfunction.
3. EGR valve base gasket improperly installed.
4. EGR valve malfunction.
5. PCM malfunction.

DTC is set when PCM detects difference in intake manifold pressure between open EGR and closed EGR is too large. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction conditions during first drive cycle. Freeze Frame Data is available and DTC is stored in the PCM memory.

1. EGR valve base gasket damaged or missing.
2. PCM malfunction.

PCM monitors input voltages from EGR valve control signals. DTC is set if PCM detects input voltage is less than or more than specified when ignition is turned on. This is an intermittent monitor. MIL does not illuminate. Freeze Frame Data is available and DTC is stored in PCM memory.

1. EGR valve malfunction.
2. Connector or terminal malfunction.
3. Short or open circuit in wiring between EGR valve and PCM.
4. Open circuit in wiring between EGR valve and main relay.

PCM compares values of front and rear HO2S inversions for a predetermined time. PCM monitors number of inversions that rear side performs while middle side inverts for a specified number of times when the following monitoring conditions are met

Monitoring Conditions

1. Engine speed 1090-3090 RPM.
2. Calculated load 16-55 percent (minimum calculated load value varies depending on engine speed).
3. Vehicle speed 16.4-64.3 MPH.

PCM detects the inversion ratio. If inversion ratio is less than threshold, PCM determines that catalyst system has deteriorated. This is a intermittent monitor (CATALYST). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. DIAGNOSTIC MONITORING TEST RESULTS and PENDING CODE are available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Three Way Catalytic (TWC) converter deterioration or malfunction.
2. Exhaust system leak.
3. Loose front HO2S.
4. Loose rear HO2S.
5. Front HO2S malfunction.

PCM measures purge line pressure/vacuum. DTC is set, if vacuum between charcoal canister and intake manifold does not reach a predetermined specification. Monitoring is performed when following monitoring conditions are met

Monitoring Conditions

1. Engine speed 1100-2700 RPM.
2. Throttle opening angle 11-25 percent.

This is an intermittent monitor (Evaporative system monitor). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Diagnostic Monitoring Test Results and Pending Code are stored if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM.

1. Purge solenoid valve malfunction.
2. Evaporative emission system leak detection pump malfunction.
3. Charcoal canister malfunction.
4. Catch tank malfunction.
5. EVAP hose damaged or loose.
6. EVAP pipe damaged.
7. PCM malfunction.

PCM measures Fuel Tank Pressure (FTP-2), which is the vacuum when a specified period of time has passed after EVAP system is sealed. PCM determines FTP pressure difference between FTP-l and FTP-2. If pressure differential exceeds threshold, PCM determines that EVAP system has a small leak. This monitor can activate when PCM determines that CONSTANT LEAK DETECTED test results are passed. PCM monitors EVAP system when driving under following conditions

Monitoring Conditions

1. FTP (FTP-2 and FTP-1) .38 in. Hg. (1.27 kPa).
2. Fuel remaining is 15-85 percent of total capacity.
3. Intake air temperature is 14-140°F (-10-60°C) when engine is first started.
4. Engine coolant temperature is 14-95°F (-10.0-35°C) when engine is first started.
5. Atmospheric pressure is more than 21.3 in. Hg. (72.2 kPa).
6. Vehicle speed is 24.5-74.5 MPH.
7. Engine speed is 1000-4000 RPM.
8. Calculated load is 9.4-65 percent.
9. Throttle opening angle is 3.13-31.6 percent.
10. Intake air temperature is 14-140°F (-10-60°C) during monitoring.
11. Engine coolant temperature is 158-212°F (70-100°C) during monitoring.

This is an intermittent monitor (Evaporative leak monitor). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Diagnostic Monitoring Test Results and Pending Code are stored if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Canister Drain Cut Valve (CDCV) malfunction.
2. Catch tank malfunction.
3. Charcoal canister malfunction.
4. Cracked fuel tank.
5. EVAP hoses damaged or loose.
6. Loose or damaged fuel filler cap.
7. Poorly installed fuel tank components.
8. Purge solenoid valve malfunction.
9. Rollover valve malfunction.

PCM monitors input voltage from purge solenoid valve just after turning ignition on. If voltage is less than 2.7 volts, PCM determines that purge solenoid valve circuit has malfunction. This is diagnostic support DTC (monitored once per key cycle). MIL does not illuminate. Freeze Frame Data is not available and DTC is not stored in PCM memory.

1. Connector or terminal 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.
5. Purge solenoid valve malfunction.

PCM monitors EVAP leak detection pump load current while evaporative leak monitor is operating. If decrease in pump load current is less than specification after reference current value is obtained, PCM determines Change Over Valve (COV) malfunction and DTC is set. This is an intermittent monitor. MIL illuminates if PCM detects malfunction in 2 consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Damaged COV.
2. Short between EVAP system leak detection pump and PCM harness connectors.
3. Damaged PCM.

PCM measures pump load current (EVAP line pressure) when a specified period has passed after EVAP system is sealed and ignition is turned off. If load does not reach reference load value or rate of load increase is lower than specified within a specified period, PCM determines that EVAP system has a very small leak.

Monitoring Condition

1. Ignition off.
2. IAT: 50-140°F (10-60°C).
3. Battery voltage: 11-14.5 volts.
4. Atmospheric pressure: 21.33 in. Hg (71.8 kPa) or more.
5. Fuel tank level: 15-85 percent.

This is an intermittent monitor (Evaporative leak monitor). MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Diagnostic Monitoring Test Results and Pending Code are stored if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Purge solenoid valve malfunction.
2. Change Over Valve (COV) in EVAP system leak detection pump malfunction.
3. Charcoal canister malfunction.
4. Catch tank malfunction.
5. Fuel cap malfunction.
6. Fuel tank malfunction.
7. Fuel pump unit poor seal.
8. EVAP hose damaged or loose.
9. EVAP pipe damaged.

DTC is set when fuel gauge sending unit operating range is less than one percent when fuel consumption is more than 4.4 gallons. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

Possible Cause

Fuel gauge sending unit malfunction.

DTC is set when fuel gauge sending unit voltage is less than .01 volt for 5 seconds. PCM determines that fuel gauge sender unit has a malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Fuel gauge sending unit malfunction.
2. PCM malfunction.
3. Short circuit between fuel gauge sending unit and PCM.
4. Short circuit between fuel gauge sending unit ground and signal circuit.

DTC is set when fuel gauge sending unit voltage is more than 5.4 volts for 5 seconds. PCM determines that fuel gauge sender unit has a malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Fuel gauge sending unit malfunction.
2. Open circuit between fuel sending unit and ground.
3. Open circuit between fuel sending unit and PCM.
4. PCM malfunction.
5. Poor connection at fuel gauge sending unit or PCM harness connectors.

DTC is set when cooling fan relay coil control circuit input is low or high. PCM determines that cooling fan relay circuit has a malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Cooling fan relay malfunction.
2. Open or short circuit between cooling fan relay and PCM.
3. Open circuit between cooling fan relay and under-dash fuse block.
4. PCM malfunction.
5. Connector or terminal malfunction.

DTC is set when vehicle speed signal is less than 2.3 MPH for 25.6 seconds or more. After following monitoring conditions are met

Monitoring Conditions

1. Shifter range is in D, S or L range (A/T).
2. Shifter in gear and clutch pedal released (M/T).
3. Charging efficiency is more than 40 percent.
4. Engine speed is more than 2000 RPM.

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction conditions during first drive cycle. Freeze Frame Data is available. Hold indicator light flashes and DTC is stored in PCM memory.

1. Damaged connector or terminal.
2. Instrument cluster malfunction.
3. Open or short circuit between output speed sensor and Transmission Control Module (TCM).
4. Open or short circuit between PCM and instrument cluster.
5. Open or short circuit between TCM and instrument cluster.
6. Open or short circuit between Vehicle Speed Sensor (VSS) and instrument cluster.
7. PCM malfunction.
8. VSS malfunction.

DTC is set when PCM monitors Idle Air Control (IAC) valve circuit voltage under following monitoring conditions and detects that IAC control signal does not change for one second. PCM determines that IAC valve circuit has malfunction.

Monitoring Conditions

1. Except when cranking engine.
2. Battery voltage more than 11 volts.
3. IAC valve actuation time is 18.1-69.9 percent.

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition during first drive cycle. Pending code is not available. Freeze Frame Data is available and DTC is stored in PCM memory.

1. IAC valve circuit malfunction.
2. Open or short circuit between IAC valve and PCM.
3. PCM malfunction.
4. Poor connection at IAC or PCM harness connectors.

DTC is set when actual engine speed is 100 RPM less than programed target speed for more than 14 seconds with brake pedal depressed (brake switch is on) and front wheels in straight ahead position (Power Steering Pressure (PSP) switch is off). This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. A/C relay control circuit malfunction.
2. Air filter or intake passage plugged.
3. Generator control circuit malfunction.
4. Idle Air Control (IAC) valve malfunction.
5. Purge solenoid valve malfunction.
6. Low engine compression or to much blow by.
7. PCM malfunction.

DTC is set when actual engine speed is 200 RPM more than programed target speed for more than 14 seconds with brake pedal depressed (brake switch is on) and front wheels in straight ahead position (Power Steering Pressure (PSP) switch is off). This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

Note. If atmospheric pressure is less than 21.3 in. Hg or intake air temperature is less than 14°F (-10°C), PCM will not monitor this circuit.

1. Idle Air Control (IAC) valve malfunction.
2. PCM malfunction.
3. Throttle cable misadjustment.
4. Throttle valve malfunction.
5. Vacuum hoses incorrectly connected.

DTC is set when vehicle speed is 37.3 MPH or more, coolant temperature is 140°F (60°C) or more and PCM receives a low Power Steering Pressure (PSP) switch signal continuously for more than 60 seconds. PCM determines that PSP switch circuit has a malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. PCM malfunction.
2. PSP switch malfunction.
3. Short circuit between PSP switch and PCM.

DTC is set when short or open circuit exists between PCM and TCM.

1. PCM malfunction.
2. Poor connection at PCM or TCM harness connectors.
3. Short or open circuit to power or ground between PCM or TCM.
4. TCM malfunction.

DTC is set when PCM detects Read Only Memory (ROM) is damaged.

PCM internal ROM damaged.

DTC is set when PCM has not received a voltage change from brake switch when brake pedal is activated at least 10 times and vehicle speed is more than 18.6 MPH and stopped repeatedly, it determines that brake switch circuit has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction conditions during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

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

DTC is set when PCM has not received a voltage change from clutch switch when clutch pedal is activated at least 10 times, vehicle speed is more than 18.6 MPH and vehicle is stopped repeatedly. PCM determines clutch switch circuit has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction conditions during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Clutch switch malfunction.
2. Open or short circuit between clutch switch and ground.
3. Open or short circuit between clutch switch and PCM.
4. PCM malfunction.

DTC is set when PCM has not received a voltage change from neutral switch when gears are shifted more than 14 times and vehicle speed is more than 18.6 MPH. PCM determines that neutral switch circuit has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Neutral switch malfunction.
2. Open or short in wiring between neutral switch and PCM.
3. Open or short in wiring between neutral switch and ground.
4. PCM malfunction.

DTC is set when PCM detects EGR boost sensor solenoid valve input is less than 2.7 volts when ignition is turned on. PCM determines that EGR boost sensor solenoid valve circuit has malfunction.

1. Connector or terminal malfunction.
2. EGR boost sensor solenoid valve malfunction.
3. Open circuit between EGR boost sensor solenoid valve and main relay.
4. Open or short circuit between EGR boost sensor solenoid valve and PCM.
5. PCM malfunction.

DTC is set when PCM backup memory voltage is less than 2.5 volts during engine cranking. PCM determines that back-up voltage circuit has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in 2 consecutive drive cycles. Pending code is available if PCM detects malfunction conditions during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Faulty ROOM fuse (10-amp).
2. Open or short circuit between PCM and battery.
3. PCM malfunction.
4. Poor connection of PCM connector.

1. DTC is set when transmission command from PCMto immobilizer unit exceeds limit.
2. There is no response from immobilizer unit.

1. Immobilizer unit malfunction.
2. Coil (immobilizer system) malfunction.
3. Key (transponder) malfunction.
4. Open in circuit between immobilizer unit and ground.
5. PCM malfunction.
6. Short or open in circuit between immobilizer unit and PCM.
7. Short or open in circuit between immobilizer unit and coil.

DTC is set when ignition key identification numbers are not registered in PCM.

Immobilizer system key identification numbers reprogram procedure (code word) was not performed after replacing PCM.

DTC is set when immobilizer unit code word is not registered in PCM.

Immobilizer system reprogram procedure (key IDs) was not performed after replacing PCM.

DTC is set when PCM does not read DTCs from output devices. PCM determines PCM has malfunction.

1. Short circuit to power in purge solenoid valve control circuit.
2. Short circuit to power in EGR valve control circuit.
3. Short circuit to power in Variable Tumble Control System (VTCS) solenoid valve control circuit.
4. Short circuit to power in EGR boost sensor solenoid valve control circuit.
5. PCM malfunction.

DTC is set when immobilizer unit code word does not match code stored in Powertrain Control Module (PCM).

Immobilizer system immobilizer unit code reprogram procedure (code word) was not performed correctly after replacing immobilizer unit or PCM.

DTC is set when identification numbers stored in immobilizer unit and PCM do not match This DTC is indicated only after immobilizer unit is replaced and system is reprogrammed.

Transfomation of key identification numbers stored in PCM.

DTC is set when PCM EEPROM is damaged.

PCM EEPROM is damaged.

DTC is set when PCM detects immobilizer system communication malfunctions more than 3 times.

1. Engine start was attempted more than 3 times under malfunction.
2. Code word mismatch.

DTC is set when PCM detects generator output voltage is less than 8.5 volts for 5 seconds with engine running. Than PCM determines that charging system has malfunction.

1. Open or short circuit between generator and PCM.
2. Loose, broken or missing generator drive belt.
3. Generator malfunction.
4. PCM malfunction.

DTC is set when PCM detects generator output is more than 18.5 volts or battery voltage is more than 16 volts for 5 seconds while engine is running. PCM determines that charging system has malfunction.

1. Generator malfunction (overcharge).
2. PCM malfunction.
3. Short circuit between generator and PCM.

DTC is set when PCM detects generator output is more than 17 volts and battery voltage is less than 11 volts for 5 seconds while engine is running. PCM determines that charging system has malfunction.

1. Battery malfunction.
2. Open or short circuit between battery and generator.
3. PCM malfunction.

DTC is set when PCM detects input voltage from Variable Tumble Control System (VTCS) vacuum switch remains high when VTCS solenoid valve is on. PCM determines that VTCS vacuum switch has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Connector or terminal malfunction.
2. Open or short circuit between VTCS vacuum switch and PCM.
3. PCM malfunction.
4. Vacuum line malfunction.
5. VTCS vacuum switch malfunction (stuck open).
6. VTCS solenoid valve malfunction (stuck open).

DTC is set when PCM detects input voltage from Variable Tumble Control System (VTCS) vacuum switch remains low when VTCS solenoid valve is off. PCM determines that VTCS vacuum switch has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Connector or terminal malfunction.
2. Short circuit between VTCS vacuum switch and PCM.
3. PCM malfunction.
4. Vacuum line malfunction.
5. VTCS solenoid valve malfunction (stuck closed).
6. VTCS vacuum switch malfunction (stuck closed).

DTC is set when PCM detects input voltage from Variable Tumble Control System (VTCS) solenoid valve remains low when VTCS solenoid valve is off. PCM determines VTCS solenoid valve has malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Open circuit between VTCS solenoid valve and man relay.
2. PCM malfunction.
3. Poor connection of VTCS solenoid valve and/or PCM harness connectors.
4. Short or open circuit between VTCS solenoid valve and PCM.
5. VTCS solenoid valve malfunction.

DTC is set if PCM detects input voltage from Variable Tumble Control System (VTCS) solenoid valve is high when VTCS solenoid valve is on. PCM determines that VTCS solenoid valve malfunction. This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

Monitoring Conditions

1. Engine speed is more than 3500 RPM.
2. ECT is less than 158°F (70°C).

1. Poor connection at PCM and/or VTCS solenoid valve harness connectors.
2. Open or short circuit between VTCS solenoid valve and PCM.
3. Open circuit between VTCS solenoid valve and main relay.
4. PCM malfunction.
5. VTCS solenoid valve malfunction.

The PCM monitors pump load current (EVAP line pressure), while evaporative leak monitor is operating. If pump load current is less than specified, PCM determines EVAP system leak detection pump motor circuit has a malfunction. This is an intermittent monitor. MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Open circuit between EVAP system leak detection pump and main relay.
2. Open or short circuit between EVAP system leak detection pump and PCM.
3. PCM malfunction.
4. Poor connection at EVAP system leak detection pump or PCM harness connectors.

Scheme 47

1. Verify Related Repair Information Availability - Turn ignition off. Connect scan tool to DLC-2. see scheme 1 Turn ignition on, engine off. Monitor for FREEZE FRAME DATA and ensure data has been recorded. Check service bulletins for repair information related to this DTC. If repair information is not available, go to next step. If repair information is available, perform diagnosis and repair as necessary. After repair, go to next step.
2. Verify Related Pending Code Or Stored DTCs - Turn ignition off, then on (engine off). Verify related Pending Code or stored DTCs. If DTC P2405 is not present with P2401, go to next step. If DTC P2405 is present with P2401, go to «DTC P2405: EVAP SYSTEM LEAK DETECTION PUMP ORIFICE FALLEN OFF»(ref-151884-S39654061762003022500000).
3. Inspect Poor Connection Of EVAP System Leak Detection Pump Connector - Turn ignition off. Disconnect EVAP system leak detection pump 4-pin harness connector. (Scheme 47) Check for poor connection at EVAP system leak detection pump connector terminals due to damaged, pulled-out pins, corrosion, etc. If connector terminals are okay, go to next step. If connector terminals are faulty, repair or replace as necessary. After repair, go to step 9.
4. Inspect EVAP System Leak Detection Pump Motor Circuit For Open - Disconnect main relay. Check continuity between EVAP system leak detection pump 4-pin harness connector terminal "A" and main relay 4-pin harness connector terminal "D" (White/Red wire). If continuity is present, go to next step. If continuity is not present, repair open circuit in White/Red wire between EVAP system leak detection pump 4-pin harness connector terminal "A" and main relay 4-pin harness connector terminal "D". See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step 9.
5. Inspect Poor Connection Of PCM Connector - Turn ignition off. Disconnect PCM 31-pin harness connector. see scheme 3 Check for poor connection at VTCS connector terminals due to damaged, pulled-out pins, corrosion, etc. If connector terminals are okay, go to next step. If connector terminals are faulty, repair or replace as necessary. After repair, go to step 9.
6. Inspect EVAP System Leak Detection Pump Motor Circuit For Short To Ground - Check continuity between ground and EVAP system leak detection pump 4-pin harness connector terminal "D" (Yellow/Black wire). If continuity is not present, go to next step. If continuity is present, repair short circuit to ground in Yellow/Black wire between EVAP system leak detection pump 4-pin harness connector terminal "D" and PCM 24-pin harness connector terminal "3K". After repair, go to step 9.
7. Inspect EVAP System Leak Detection Pump Motor Circuit For Open Circuit - Check continuity between EVAP system leak detection pump 4-pin harness connector terminal "D" and PCM 24-pin harness connector terminal "3K" (Yellow/Black wire). If continuity is present, go to next step. If continuity is not present, repair open circuit in Yellow/Black wire between EVAP system leak detection pump 4-pin harness connector terminal "D" and PCM 24-pin harness connector terminal "3K". See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step 9.
8. Inspect EVAP System Leak Detection Pump - Perform EVAP system leak detection pump inspection. See «FUEL EVAPORATIVE SYSTEM (MIATA & MPV)»(ref-151892-S26634580692003010900000) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article. If EVAP system leak detection pump is okay, go to next step. If EVAP system leak detection pump is faulty, replace EVAP system leak detection pump. After repair, go to next step.
9. Verify Troubleshooting Of DTC P2401 Completed - Return vehicle to original condition. Using scan tool, clear DTCs from PCM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151884-S38555540052003010900000) under SELF-DIAGNOSTIC SYSTEM. Start engine and run DRIVE MODES 1, 2 and 3. See «DRIVE MODES»(ref-151884-S01000799312003010900000) under SELF-DIAGNOSTIC SYSTEM.Monitor for pending DTCs. If same DTC is not present, go to next step. If same DTC P2401 is present, replace PCM. For PCM removal and installation, see «POWERTRAIN CONTROL MODULE»(ref-151901-S39392855062003010900000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article. After repair, go to next step.
10. Verify After Repair Procedure - Using scan tool, perform After Repair Procedure. See «AFTER REPAIR PROCEDURE»(ref-151884-S39899430132003022600000). If no other DTCs are present, testing is complete. If any other DTC is present, go to applicable test and repair.

The PCM monitors pump load current (EVAP line pressure), while evaporative leak monitor is operating. If pump load current is more than specified, PCM determines EVAP system leak detection pump motor circuit has a malfunction. This is an intermittent monitor. MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Short circuit to power between EVAP system leak detection pump and PCM.
2. PCM malfunction.

The PCM monitors pump load current (EVAP line pressure), while evaporative leak monitor is operating. After obtaining reference current value, if the time in which pump load current reaches reference current value is less than specification, PCM determines air filter has a malfunction. This is an intermittent monitor. MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. Air filter clogging.
2. EVAP hose bending.
3. PCM damaged.

The PCM monitors pump load current (EVAP line pressure), while evaporative leak monitor is operating. If current is lower than specification while PCM obtains reference current value, PCM determines EVAP system leak detection pump orifice has a malfunction. This is an intermittent monitor. MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. EVAP system leak detection pump orifice fallen off.
2. EVAP system leak detection pump motor malfunction.
3. PCM malfunction.

The PCM monitors pump load current (EVAP line pressure), while evaporative leak monitor is operating. If current is higher than specification while PCM obtains reference current value, PCM determines EVAP system leak detection pump orifice has a malfunction. This is an intermittent monitor. MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles. Pending Code is available if PCM detects malfunction condition during first drive cycle. Freeze Frame Data is available and DTC is stored in PCM memory.

1. EVAP system leak detection pump orifice clogging.
2. EVAP system leak detection pump motor malfunction.
3. PCM malfunction.

The PCM monitors pump load current (EVAP line pressure), while evaporative leak monitor is operating. When either of following is detected 28 times or more successively, PCM determines EVAP system leak detection pump heater has a malfunction

1. While obtaining reference current value, change in pump load current exceeds specification.
2. After obtaining reference current value, pump load current is kept lower than maximum pump load current for more than specified time.

This is an intermittent monitor. MIL illuminates if PCM detects malfunction condition. Pending Code is available if PCM detects malfunction condition. Freeze Frame Data is available and DTC is stored in PCM memory.

1. EVAP system leak detection pump heater malfunction.
2. PCM malfunction.

Incorrect reference voltage.

Reference voltage circuit malfunction at following systems components

1. Exhaust Gas Recirculation (EGR) boost sensor.
2. Throttle Position (TP) sensor.
3. Transmission Control Module (TCM).

AFTER REPAIR PROCEDURE

Connect scan tool. Turn ignition off, then on (engine off). Check for DTCs. Select CLEAR. Select TRIGGER. Select CANCEL. Turn ignition off.