P0401 Exhaust Gas Recirculation Flow Insufficient Detected
Too little exhaust gas is being recirculated.
Common causes
- Clogged EGR passages
- Stuck-closed EGR valve
- Faulty EGR position sensor
Symptoms
- Check engine light
- Pinging or knocking
- Higher NOx emissions
What to check
- Clean EGR passages
- Check valve movement
- Check position feedback
Manufacturers may add their own detail to generic codes. If your vehicle shows a different description for P0401, follow the service information for that make and model.