DTC P0400: EGR Function: Procedure
- Check exhaust system for leaks. Repair as necessary and retest system. If no leaks are found, start engine and warm to normal operating temperature. Disconnect vacuum hose from EGR valve. Check for vacuum at hose. Vacuum should not exist when engine is idling. If vacuum exists, repair vacuum hose routing and retest system. If vacuum does not exist, go to next step.
- Raise drive wheels, and support vehicle. Shift transmission into 1st gear. Check for vacuum while quickly increasing engine speed to 4000 RPM. Vacuum should exist while increasing engine speed. If vacuum is as specified, go to next step. If vacuum is not as specified, go to step 4.
- Remove EGR valve. Using a hand vacuum pump, apply vacuum to EGR valve. EGR valve should open without sticking. If EGR valve operates as specified, test is complete. If EGR valve does not open, clean or replace EGR valve and retest system.
- Inspect vacuum hose for blockage, leak or misrouting. Repair as necessary. If vacuum hose is okay, increase engine speed to 2000 RPM. Listen for EGRC solenoid operating sound while disconnecting and connecting EGRC solenoid harness connector. See Fig 1. If operating sound is heard, go to next step. If operating sound is not heard, check EGR solenoid and circuit. See DTC P1400: EGR CONTROL (EGRC) SOLENOID . Repair as necessary and retest system.
- Remove EGRC solenoid. Using jumper wires, apply battery voltage and ground to EGRC solenoid terminals. See Fig 2. Air should flow between ports "A" and "B". Air should not flow between ports "A" and "C". Remove jumper wires. Air should not flow between ports "A" and "B". Air should flow between ports "A" and "C". EGRC solenoid should switch in one second or less. If operation is as specified, go to next step. If operation is not as specified, replace EGRC solenoid and retest system.
- Remove EGRC-BPT. Plug one vacuum port and apply vacuum to other vacuum port. Vacuum should not hold. Apply about 3.94 in. H2 O (.98 kPa) of pressure to backpressure port. Vacuum should hold. If operation is as specified, go to next step. If operation is not as specified, replace EGRC-BPT and retest system.
- Remove EGR temperature sensor located near EGR valve. Place EGR temperature sensor in heated water. Measure resistance between EGR temperature sensor terminals, with water at specified temperatures. See EGR TEMPERATURE SENSOR RESISTANCE table. If resistance is as specified, go to next step. If resistance is not as specified, replace EGR temperature sensor and retest system.
- No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
EGR TEMPERATURE SENSOR RESISTANCE
| Temperature - °F (°C) | K/Ohms |
|---|---|
| 32 (0) | 680-1110 |
| 122 (50) | 90-120 |
| 212 (100) | 17-24 |