DTC P0401 [L3]

BME010200400W08

DTC P0401

EGR flow insufficient detected

DETECTION CONDITION

• PCM monitors difference in intake manifold pressures when EGR is operated and when it is stopped. If the difference is too small, PCM determines that EGR flow insufficient.
Diagnostic support note
• This is an intermittent monitor (EGR).
• The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
• PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
• FREEZE FRAME DATA is available.
• The DTC is stored in the PCM memory.

POSSIBLE CAUSE

• EGR valve malfunction
• MAP sensor malfunction
• EGR gasket malfunction
• PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION

1
PERFORM DTC CONFIRMATION PROCEDURE
• Perform DTC CONFIRMATION PROCEDURE.
• Is same DTC present?
Yes
Go to next step.
No
Intermittent concern exists. Go to INTERMITTNENT CONCERN TROUBLESHOOTING procedure.
2
INSPECT VACUUM HOSE CONDITION
• Inspect vacuum hoses for clogs, any damages, frozen, or vacuum leakage.
• Is there any malfunction?
Yes
Replace vacuum hoses, then go to Step 6.
No
Go to next step.
3
INSPECT EGR VALVE MALFUNCTION
• Perform EGR valve inspection.
• Is EGR valve okay?
Yes
Go to next step.
No
Replace EGR valve, then go to Step 6.
4
INSPECT MAP SENSOR MALFUNCTION
• Perform MAP sensor inspection.
• Is EGR valve okay?
Yes
Go to next step.
No
Replace MAP sensor, then go to Step 6.
5
INSPECT EGR VALVE PASSAGE
• Turn ignition switch to off.
• Remove EGR valve.
• Is gasket installation normal?
Yes
Go to next step.
No
Install gasket correctly, then go to next step.
6
VERIFY TROUBLESHOOTING OF DTC P0401 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear the DTC from the PCM memory using the WDS or equivalent.
• Perform KOER self-test.
• Is the same DTC present?
Yes
Replace PCM, then go to next step.
No
Go to next step.
7
VERIFY AFTER REPAIR PROCEDURE
• Perform "After Repair Procedure".
• Is there any DTC present?
Yes
Go to applicable DTC inspection.
No
Troubleshooting completed.