DTC P0401: EGR Insufficient Flow
- Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
- Clear the DTC with the HDS.
- 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.
- 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 158°F(70°C)
- A/T in D, or M/T in 4th
- Drive at a steady speed between 55- 75 mph (88- 120 km/h) 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 - Clean the intake manifold EGR port and EGR pipe (see EGR PIPE REPLACEMENT ) with throttle plate cleaner. Also, clean the passage inside the EGR valve with throttle plate 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 to LOCK (0), or press the engine start/stop button to select the OFF mode.
- Replace the EGR valve (see EGR VALVE REPLACEMENT ).
- Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
- 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 158°F(70°C)
- A/T in D, or M/T in 4th
- Drive at a steady speed between 55- 75 mph (88- 120 km/h) for at least 10 seconds
- During the drive, decelerate (with the throttle fully closed) for 5 seconds
- Check for Pending or Confirmed 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 Pending or Confirmed 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 ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
- Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158°F(70°C)
- A/T in D, or M/T in 4th
- Drive at a steady speed between 55- 75 mph (88- 120 km/h) for at least 10 seconds
- During the drive, decelerate (with the throttle fully closed) for 5 seconds
- Check for Pending or Confirmed 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 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 - If 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 Pending or Confirmed 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.