P0172: System Too Rich (Bank 1)
System: Fuel trim · Priority: medium
What P0172 means
The control module detected a condition matching the generic definition System Too Rich (Bank 1). A trouble code identifies what the module detected; it does not automatically identify the failed part.
Useful next checks
- Check for leaking injectors or excessive fuel pressure.
- Inspect MAF/MAP data and coolant-temperature plausibility.
- Review fuel trims and O2/A/F sensor data before replacing parts.
Why vehicle context matters
The same generic code can have different diagnostic paths depending on engine, calibration, wiring layout, service bulletins and related codes. Freeze-frame and live data can help establish when the fault occurred.
Need a scanner for P0172?
Build a direct VeroRoad page for your year, make and model. It will open the vehicle-specific read-codes / diagnostic context instead of a generic product list.