OBD2 fault code
ModerateP0401
Exhaust Gas Recirculation Flow Insufficient
The code identifies an implausible condition in the monitored system. The component named in the code is not automatically the defective part.
What does P0401 mean?
Exhaust Gas Recirculation Flow Insufficient. The engine or vehicle control system detected that a measured value, control response, or communication signal was outside the expected range.
Common symptoms
- hesitation at part load
- power loss or limp mode
- smoke and increased emissions
Likely causes
- EGR valve carboned up or sticking
- vacuum, actuator, or position sensor fault
- intake or exhaust passages restricted
Sensible diagnostic order
- compare commanded and actual EGR position
- inspect valve and passages for deposits
- test vacuum or electrical control
Can I continue driving?
Driving may be possible, but diagnosis should be performed soon. If the check-engine light flashes, the engine shakes strongly, warning messages increase, or power drops significantly, stop and arrange professional assistance.
This information is a diagnostic aid and does not replace inspection by a qualified workshop. Manufacturer-specific definitions may differ.
FAQ
Can I continue driving with P0401?
Driving may be possible, but diagnosis should be performed soon.
Does P0401 always identify a defective part?
No. A fault code identifies a monitored system or implausible condition. Wiring, voltage, leaks, and related components must also be checked.
How can DiagnostiX help with P0401?
DiagnostiX reads the code from the vehicle, assigns it to the vehicle profile, and displays relevant live values and a structured explanation.