DTC Troubleshooting: P0401 (80)

DTC P0401:  EGR Insufficient Flow

1.Turn the ignition switch ON (II).

2.Do the DTC CLEAR in the CLEAR MENU with the HDS.

3.Do the EGR TEST in the INSPECTION MENU with the HDS.

Is the result OK?


YES - Go to 4.


NO - Go to 6.


4.Test-drive under following conditions.
  • Engine Coolant temperature more than 70°C (158°F)
  • Transmission in 4th gear
  • Vehicle speed at 20 km/h (13 mph) or more, and engine speed between 1,000 rpm (min-1) and 5,000 rpm (min-1)
  • During the drive, decelerate (with the throttle fully closed) for 5 seconds, and repeat that 5 times

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

is it FAILED?


YES - Remove the EGR valve and intake manifold, then clean the intake manifold port with carburetor cleaner, then go to 8.


NO - If it is PASSED, intermittent failure, system is OK at this time. If it is EXECUTING, keep the driving condition continually untill a result comes on. If it is Out of CONDITION, go to 4 and recheck.


6.Turn the ignition switch OFF.

7.Replace the EGR valve.

8.Turn the ignition switch ON (II).

9.Do the ECM RESET in the CLEAR MENU with the HDS.

10.Do the ETCS learn procedure.

11.Test-drive under following conditions.
  • Engine Coolant temperature more than 70°C (158°F)
  • Transmission in 4th gear
  • Vehicle speed at 20 km/h (13 mph) or more, and engine speed between 1,000 rpm (min-1) and 5,000 rpm (min-1)
  • During the drive, decelerate (with the throttle fully closed) for 5 seconds, and repeart that 5 times

12.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, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC troubleshooting.


NO - Go to 13.


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

Is it PASSED?


YES - Troubleshooting is complete.n


NO - If is it FAILED, then go to 1 and recheck. If it is EXECUTING, keep the driving condition continuity until a result comes on. If it is Out of CONDITION, go to 11 and recheck.