P0172 on BMW — System Too Rich, Bank 1
BMW
Verified1 source
1 source
- Official data (NHTSA)official_feed
What P0172 means
Caution — monitor closely
Long-term fuel trim has gone negative — the ECU keeps reducing fuel to compensate for excess fuel or insufficient air.
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General information, not a diagnosis or repair instruction. Always confirm with a qualified mechanic for your specific vehicle.
Common causes
- MAF sensor over-reporting airflow
- Leaking fuel injector
Symptoms
- Gasoline smell
- Повышенный расход топлива
- Black smoke from the exhaust
What to check first
- Check fuel trim with a scan tool
- Inspect injectors for leaks
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