DTC P0401: EGR Insufficient Flow
- Turn the ignition switch ON (II).
- Clear the DTC with the HDS.
- Start the engine. Hold the engine speed at 3,000 RPM (min -1 ) without load (in Park or neutral) until the radiator fan comes on, then let it idle.
- Do the EGR TEST in the INSPECTION MENU with the HDS.
Is the result OK?
YES -Go to step 5.
NO -Go to step 7.
- Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 70 °C(158°F)
- A/T in D position (M/T in 4th gear)
- Drive at a steady speed between 88-120 km/h (55-75 mph) for at least 10 seconds
- During the drive, decelerate (with the throttle fully closed) for 5 seconds
- Monitor the OBD STATUS for DTC P0401 in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
YES -Remove the EGR plate (see INTAKE MANIFOLD REMOVAL AND INSTALLATION ), and clean the intake manifold port with throttle plate and induction cleaner, then go to step 9.
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 EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 5 and recheck.
- Turn the ignition switch OFF.
- Replace the EGR valve (see EGR VALVE REPLACEMENT ).
- Turn the ignition switch ON (II).
- Reset the ECM/PCM with the HDS.
- Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
- Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 70 °C (158 °F)
- A/T in D position (M/T in 4th gear)
- Drive at a steady speed between 88-120 km/h (55-75 mph) for at least 10 seconds
- During the drive, decelerate (with the throttle fully closed) for 5 seconds
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0401 indicated?
YES -Check for poor connections or loose terminals at the EGR valve and the ECM/PCM. If the connections are OK, go to step 15.
NO -Go to step 14.
- Monitor the OBD STATUS for DTC P0401 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 13, 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 EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 12.
- Update the ECM/PCM if it does not have the latest software (see UPDATING THE ECM/PCM ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
- Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 70 °C (158 °F)
- A/T in D position (M/T in 4th gear)
- Drive at a steady speed between 88-120 km/h (55-75 mph) for at least 10 seconds
- During the drive, decelerate (with the throttle fully closed) for 5 seconds
- Check for Temporary DTCs or DTCs with the HDS.
Is DTCs P0401 indicated?
YES -Check for poor connections or loose terminals at the EGR valve and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 16. If the ECM/PCM was substituted, go to step 1.
NO -Go to step 18.
- Monitor the OBD STATUS for DTC P0401 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -lf the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ). If any other Temporary DTCs or DTCs were indicated in step 17, 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. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 16. If the ECM/PCM was substituted, go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 16.