Diagnostic Procedure
- Inspect vehicle for intake vacuum leaks and exhaust system leaks. Repair as necessary. Go to next step.
- Check Vacuum Source To EGR Valve. Start engine and allow it to reach normal operating temperature. Disconnect vacuum hose from EGR valve and check for vacuum. At idle, ensure vacuum does not exist. Check for vacuum when engine speed is raised to 2000-4000 RPM. If vacuum exists, go to next step. If vacuum does not exists, check vacuum hoses for restrictions, misrouting, cracks or improper connection. If not faults are found, go to next step.
- EGR Valve. Test EGR valve. See EGR VALVE under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM/COMPONENT TESTS article. If okay, go to next step.
- Check EGRC Solenoid. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a jumper wire, connect PCM harness connector terminal No. 103 (Blue/White wire) to ground. Check operating sound (clicking) of EGRC solenoid while disconnecting and reconnecting jumper wire to ground. If solenoid is not functioning properly, repair or replace solenoid as required. If solenoid is functioning properly, go to next step.
- Disconnect EGRC solenoid harness connector. Apply battery voltage and ground to EGRC solenoid terminals. See Fig 1. With battery voltage applied, air should pass between ports "A" and "B". Air should not pass between ports "A" and "C". With no voltage applied, air should pass between ports "A" and "C". Air should not pass between ports "A" and "B". Replace EGRC solenoid if airflow is not as specified. If solenoid is okay, check vacuum hoses for restrictions or misrouting, and go to next step.
- Check EGR Temperature Sensor. Ensure EGR temperature sensor is not damaged or contaminated. Check PCM and EGR temperature sensor harness connectors for damage, corrosion or pushed-out pins. Repair if necessary. If no problems are found, ensure ignition is off. Measure resistance between EGR temperature sensor terminals as follows:
- At 32°F (0°C), resistance should be 7.9-9.7 megohms.
- At 122°F (50°C), resistance should be .57-.70 megohms.
- At 212°F (100°C), resistance should be .08-.10 megohms.
If resistance is not as specified, replace EGR temperature sensor. If resistance is as specified, disconnect harness connectors in circuit and check for damage or corrosion. If fault is still present, go to DTC P0402: EGR CONTROL BACKPRESSURE TRANSDUCER (EGRC-BPT) VALVE .