OBD-II diagnostic trouble code
P0401Caution
Exhaust Gas Recirculation Flow Insufficient Detected
Not enough exhaust gas is being recirculated back into the intake, most commonly from a carbon-clogged EGR valve or passage restricting flow.
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Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.
Frequently asked questions
Can I drive with P0401?
You can usually keep driving with P0401, but don't put it off — the underlying cause can get worse or lead to further damage the longer it goes unaddressed. Get it diagnosed as soon as you reasonably can.
How much does it cost to fix P0401?
The cost varies too much by cause and vehicle to give a single figure here — a diagnosis will narrow it down.
What causes P0401?
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief