Carbon-clogged EGR valve. Blocked EGR passages. Faulty EGR position sensor. Failed EGR vacuum solenoid. Blocked EGR cooler.

Which cars are affected by P0401?

P0401 is most commonly reported on Vauxhall, Ford, Volkswagen, Peugeot, Renault vehicles, but can appear on any make.

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P0401

Medium severity

Exhaust Gas Recirculation (EGR) Flow Insufficient

The EGR system is not flowing enough exhaust gas back into the intake. This is a common issue on diesel and petrol engines, often caused by carbon buildup.

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Common causes of P0401

1Carbon-clogged EGR valve

2Blocked EGR passages

3Faulty EGR position sensor

+2 more causes

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Commonly affected vehicles

VauxhallFordVolkswagenPeugeotRenault

P0401 can appear on any vehicle — these are the makes where it is most frequently reported.

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Related fault codes

P0171Medium

System Too Lean (Bank 1)

P0300High

Random/Multiple Cylinder Misfire Detected

P0420Medium

Catalyst System Efficiency Below Threshold (Bank 1)

P0172Medium

System Too Rich (Bank 1)