P0172: System Too Rich (Bank 1)
MediumPowertrainFuel Metering
What does P0172 mean?
P0172 is a diagnostic trouble code indicating "System Too Rich (Bank 1)". The engine is running with too much fuel relative to air (rich condition). This wastes fuel, increases emissions, and can foul spark plugs or damage the catalytic converter over time.
Common causes
- Leaking fuel injector
- Faulty fuel pressure regulator
- Dirty or stuck-open purge valve
- Contaminated MAF sensor
- Faulty O2 or air/fuel ratio sensor
What should you do?
Schedule a diagnostic appointment at your earliest convenience. The vehicle is generally safe to drive short distances, but the underlying issue should be addressed to prevent it from worsening.
Get a diagnosis for YOUR car
Code P0172 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.