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P0401: EGR Flow Insufficient
The EGR system did not move enough exhaust gas when the PCM commanded it open.
Common causes
- Clogged EGR passages
- Failed EGR valve
- DPFE or flow sensor fault
- Vacuum control issue
This free page explains the code. A Shop Brief adapts the next steps to your year, make, model, and full code stack.
Related codes:
P0455P0171P0133 Pricing Sample brief