DTC Troubleshooting: P0401
DTC P0401: EGR Insufficient Flow
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0401 EGR Insufficient Flow
     

1.
EGR valve check:

EGR valve check
?1.
Press the engine start/stop button to select the ON mode.

?2.
Clear the DTC with the HDS.


?3.
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.

?4.
Do the EGR TEST with the HDS.

  

Is the result OK?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
2.
Problem verification:

Problem verification
?1.
Test-drive under these conditions:
Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
A/T in D, M/T in 4th
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 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, then do the repair verification.
     
NO
     
     
     
If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the EGR valve and the PCM. 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.
Repair verification (OBD STATUS check):

?1.
Press the engine start/stop button to select the OFF mode.

?2.
Reconnect all connectors.

?3.
Press the engine start/stop button to select the ON mode.

?4.
Reset the PCM with the HDS.


?5.
Do the PCM idle learn procedure.

?6.
Test-drive under these conditions:
Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
A/T in D, M/T in 4th
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 4 seconds

Signal
Current conditions
Values
Unit
ECT SENSOR 1
    
VEHICLE SPEED
    

?7.
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 PASSED, FAILED, EXECUTING, or OUT OF CONDITION?

     
PASSED
     
     
     
Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting.?
     
FAILED
     
     
     
Troubleshooting is incomplete. Go to step 1 and recheck.
     
EXECUTING
     
     
     
Keep the test condition until a result comes on.
     
OUT OF CONDITION
     
     
     
Meet the test condition, and check the OBD STATUS again.