MasterTuning Fault code dictionary (DTC)

P0172 — Rich mixture, bank 1

Severity: Warning Can you drive? Yes, no known limitation Make: All makes (OBD-II standard)
MeaningYour engine computer detected too much fuel and not enough oxygen in the exhaust gases for the first cylinder bank. This means the engine is running rich, which washes oil from cylinder walls and ruins the catalytic converter over time.
FamilyPowertrain (P)

Typical symptoms

Strong smell of unburnt fuel from the exhaust
Black smoke from the tailpipe under acceleration
Engine hesitation or rough idling when stopped
Noticeable increase in fuel consumption

Common causes

Dirty or failing mass air flow sensor
Stuck or leaking fuel injector
Faulty oxygen sensor giving a false reading
Blocked or restricted air filter

What to do

Have a technician check the mass air flow sensor and fuel trim live data as soon as possible. Continuing to drive with a rich mixture can permanently damage your catalytic converter and spark plugs.

Frequently asked questions

What does code P0172 mean?

Rich mixture, bank 1. Your engine computer detected too much fuel and not enough oxygen in the exhaust gases for the first cylinder bank. This means the engine is running rich, which washes oil from cylinder walls and ruins the catalytic converter over time.

Can I keep driving with code P0172 active?

Yes, no known limitation

Common causes — P0172

Dirty or failing mass air flow sensor Stuck or leaking fuel injector Faulty oxygen sensor giving a false reading Blocked or restricted air filter

How do you fix code P0172?

Have a technician check the mass air flow sensor and fuel trim live data as soon as possible. Continuing to drive with a rich mixture can permanently damage your catalytic converter and spark plugs.

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