DTC Troubleshooting: P0401 (80)

DTC P0401: EGR Insufficient Flow

1. Turn the ignition switch ON (II).

1. Clear the DTC with the HDS.

1. 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.

1. 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 .

1. Test-drive under these conditions:
   - Engine coolant temperature above 70 °C (158 °F)
   - Transmission in 4th gear (A/T in D position)
   - Vehicle speed at 40 km/h (25 mph) or more, and engine speed between 1,100 rpm (min −1 ) and 3,000 rpm (min −1 )
   - During the drive, decelerate (with the throttle fully closed) for 5 seconds

1. Monitor the OBD STATUS for DTC P0401 in the DTCs MENU with the HDS.

Does the screen indicate FAILED?

YES | - | Remove the EGR plate and clean the intake manifold port with carburetor cleaner, then go to Step 9 .
NO | - | If the screen indicates PASSED, intermittent failure, system is OK at this time. If the screen indicates EXECUTING, keep the driving condition continually until a result comes on. If the screen indicates OUT OF CONDITION, go to Step 5 and recheck.

1. Turn the ignition switch OFF.

1. Replace the EGR valve.

1. Turn the ignition switch ON (II).

1. Reset the ECM/PCM with the HDS.

1. Do the ECM/PCM idle learn procedure.

1. Test-drive under these conditions:
   - Engine coolant temperature above 70 °C (158 °F)
   - Transmission in 4th gear (A/T in D position)
   - Vehicle speed at 40 km/h (25 mph) or more, and engine speed between 1,100 rpm (min −1 ) and 3,000 rpm (min −1 )
   - During the drive, decelerate (with the throttle fully closed) for 5 seconds

1. Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES | - | If DTC P0401 is indicated, check for poor connections or loose terminals at the EGR valve and the ECM/PCM, then go to Step 1 . If connections are OK, go to Step 15 . If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO | - | Go to Step 14 .

1. Monitor the OBD STATUS for DTC P0401 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES | - | Troubleshooting is complete.■
NO | - | If the screen indicates FAILED, go to Step 1 and recheck. If the screen indicates EXECUTING, keep the driving condition continually until a result comes on. If the screen indicates OUT OF CONDITION, go to Step 12 and recheck.

1. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.

1. Test-drive under these conditions:
   - Engine coolant temperature above 70 °C (158 °F)
   - Transmission in D position
   - Vehicle speed at 40 km/h (25 mph) or more, and engine speed between 1,100 rpm (min −1 ) and 3,000 rpm (min −1 )
   - During the drive, decelerate (with the throttle fully closed) for 5 seconds

1. Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES | - | If DTC P0401 is indicated, check for poor connections or loose terminals at the EGR valve and the ECM/PCM, then go to Step 1 . If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO | - | If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM. ■