DTC P0400 - EGR Function
- Check Vacuum Source To EGR Valve - Start engine and bring to operating temperature. With engine speed at about 2000 RPM, disconnect vacuum hose to EGR valve. See Fig 1. If vacuum is not present, go to next step. If vacuum is present, inspect EGR valve and EGRC-BPT valve. See SYSTEM/COMPONENT TESTS article. Replace EGR valve and/or EGRC-BPT valve if necessary and perform FINAL CHECK .
- Check Component - Turn ignition on. Disconnect and reconnect EGRC solenoid harness connector. If EGRC solenoid clicks each time connector is connected or disconnected, go to next step. Replace EGRC solenoid if it does not click.
- Check EGRC Solenoid - Disconnect EGRC solenoid. Apply battery voltage and ground to terminals No. 1 and 2. See Fig 2. 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.
- Check EGR Temperature Sensor
- Remove EGR temperature sensor. Immerse sensor in fluid. Measure resistance of EGR temperature sensor while varying temperature of fluid. Replace sensor if resistance is not as specified. See EGR TEMPERATURE SENSOR RESISTANCE table. If resistance is correct, go to next step.EGR TEMPERATURE SENSOR RESISTANCE (1)
Temperature - °F (°C) (2) Ohms 32 (0) 7.9-9.7 122 (50) .57-70 212 (100) .08-1.0 (1) Heat sensor in fluid and measure resistance across sensor terminals. (2) Megohms are given. - Check ECM and EGR temperature sensor harness connectors for damage, corrosion or pushed-out pins. Repair if necessary. If fault is still present, replace EGR temperature sensor.