DTC P0401

DTC P0401  : EGR Insufficient Flow

NOTE:  Before you troubleshoot, review the general troubleshooting information .

DTC (PGM-FI)

1. EGR valve check

   -1. Turn the vehicle to the ON mode.

   -2. Clear the DTC with the HDS.

   -3. Enter the maintenance mode, then start the engine .

   -4. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.

   -5. Select the EGR TEST in the Function Test Menu with the HDS

   EGR Test

   Is the result OK?

   YES 

   Go to step 2.

   NO 

   Replace the EGR valve .

2. Problem verification:

   Test-drive the vehicle under these conditions:

   • Engine coolant temperature (ECT SENSOR 1) above 158 deg.F (70 deg.C)
   • Transmission in D
   • Drive the vehicle at a steady speed between 15-75 mph (24-120 km/h) for at least 5 seconds
   • Drive the vehicle at a steady speed between 55-75 mph (90-120 km/h) for at least 10 seconds
   • During the drive, decelerate (with the throttle fully closed) for at least 4 seconds

   Signal	Current conditions
   	Values	Unit
   ECT Sensor 1
   Vehicle Speed

   -2. Monitor the OBD STATUS for DTC P0401 in the DTCs MENU with the HDS.

   DTC Description	OBD STATUS
   P0401 EGR Insufficient Flow

   Does the HDS indicate FAILED?

   YES 

   Clean the intake manifold EGR port with throttle plate cleaner. Also, clean the passage inside the EGR valve with throttle plate cleaner.

   NO 

   If the HDS indicates PASSED, there is an intermittent failure and the system is OK at this time. Check for poor connections or loose terminals at the EGR valve and the PCM. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot . If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, meet the test condition and recheck.