Check Engine Codes / P0401
P0401 Code
Exhaust Gas Recirculation Flow Insufficient
What it means
The EGR system, which recirculates a little exhaust to cool combustion, isn't flowing enough — usually carbon buildup or a sticking valve.
Can you keep driving?
Yes. May ping/knock under load and fail emissions testing until fixed.
Common causes
Listed most-common first. Fix cost depends on which one it turns out to be — check your quote free below.
⚠️ Don't get ripped off
On many engines the EGR passages just need cleaning, not a new valve. Ask whether cleaning was attempted before approving a full valve replacement.
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Related codes
Informational only — codes share symptoms across vehicles, so proper diagnosis on your specific car always comes first.