DTC Troubleshooting

DTC Troubleshooting: P0400

DTC P0400: EGR System Leak Detected

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information. Initial Inspection and Diagnostic Overview

1. Check for a loose or damaged EGR pipe.

Is the EGR pipe OK?
YES - Go to step 2.

NO - Reconnect or replace the EGR pipe, then go to step 7.


2. Start the engine. Hold the engine speed at 3,000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.

3. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)

- A/T in D, M/T in 4th

- Vehicle speed at 25 mph (40 km/h) for 5 minutes or more

- Maintain the vehicle speed at 32 mph (50 km/h) for 5 minutes or more with cruise control set

4. Monitor the OBD STATUS for DTC P0400 in the DTCs MENU with the HDS.

Does the screen indicate FAILED?
YES - Go to step 5.

NO - If the screen indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the EGR valve and the ECM/PCM. If the screen indicates NOT COMPLETED, go to step 3 and recheck.


5. Turn the ignition switch to LOCK (0).

6. Replace the EGR valve. Service and Repair

7. Turn the ignition switch to ON (II).

8. Reset the ECM/PCM with the HDS.

9. Do the ECM/PCM idle learn procedure. ECM/PCM Idle Learn Procedure (A/T)

10. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)

- A/T in D, M/T in 4th

- Vehicle speed at 25 mph (40 km/h) for 5 minutes or more

- Maintain the vehicle speed at 32 mph (50 km/h) for 5 minutes or more with cruise control set

11. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0400 indicated?
YES - Check for poor connections or loose terminals at the EGR valve and the ECM/PCM, then go to step 1.

NO - Go to step 12.


12. Monitor the OBD STATUS for DTC P0400 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 11, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the EGR valve and the ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 10.