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DTC P0401

DTC P0401  : EGR Insufficient Flow

NOTE:  Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Fuel and Emissions Systems .

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

DTC (PGM-FI)

  1. EGR valve check

    - 1. Turn the vehicle to the ON mode.

    - 2. Clear the DTC with the HDS.

    - 3. 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. Do the EGR TEST with the HDS.

    EGR TEST

    Is the result OK?

    YES 

    Go to step 2.

    NO 

    Replace the EGR valve .

  2. Problem verification

    - 1. Test-drive under these conditions:

    • Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °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 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, 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 freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot - Refer to: How to Troubleshoot the Fuel and Emissions Systems . If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, meet the test conditions and recheck.