P0401: Exhaust Gas Recirculation Flow Insufficient Detected
System: EGR / emissions · Priority: medium
What P0401 means
The control module detected a condition matching the generic definition Exhaust Gas Recirculation Flow Insufficient Detected. A trouble code identifies what the module detected; it does not automatically identify the failed part.
Useful next checks
- Inspect EGR passages for carbon restriction.
- Command the EGR valve with a capable scan tool if supported.
- Check differential-pressure or position-sensor data where applicable.
Why vehicle context matters
The same generic code can have different diagnostic paths depending on engine, calibration, wiring layout, service bulletins and related codes. Freeze-frame and live data can help establish when the fault occurred.
Need a scanner for P0401?
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