Faulty MAF sensor. Leaking fuel injectors. Stuck closed purge valve. Faulty O2 sensor. High fuel pressure.

Which cars are affected by P0172?

P0172 is most commonly reported on BMW, Mercedes-Benz, Ford, Vauxhall, Volkswagen vehicles, but can appear on any make.

P0172

Medium severity

System Too Rich (Bank 1)

The engine is running rich on bank 1 — too much fuel relative to air is entering the combustion chamber, leading to poor fuel economy and potential catalyst damage.

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Common causes of P0172

1Faulty MAF sensor

2Leaking fuel injectors

3Stuck closed purge valve

+2 more causes

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Commonly affected vehicles

BMWMercedes-BenzFordVauxhallVolkswagen

P0172 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)

P0401Medium

Exhaust Gas Recirculation (EGR) Flow Insufficient