System Too Rich Bank 1
The engine is running too rich on bank 1, meaning too much fuel or not enough air.
Informational only. Consult a qualified mechanic.
- Dirty air filter
- Leaking fuel injector
- Faulty O2 sensor
- High fuel pressure
- Faulty MAF sensor
Replace air filter, check fuel injectors, and inspect O2 sensors.
What does P0172 mean?
The P0172 OBD-II diagnostic trouble code (DTC) indicates: system too rich bank 1. This is a medium-severity powertrain code that your vehicle's onboard diagnostics system triggers when the engine is running too rich on bank 1, meaning too much fuel or not enough air. If your check engine light is on with this code, the vehicle is generally safe to drive, but you should have it inspected soon.
Use Your Service Book to log this diagnostic trouble code to your vehicle's service history, track repairs, and get maintenance reminders — all for free.
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