P0172 System Too Rich (Bank 1)
What does P0172 mean?
P0172 — System Too Rich (Bank 1) (bank 1). This is an OBD-II diagnostic trouble code a scanner retrieves when your vehicle's computer detects system too rich (bank 1) on bank 1. The level of risk depends on how the vehicle is currently running and how long you've been driving with the light on.
Common causes of P0172
- Faulty mass air flow sensor over-reporting airflow
- Clogged air filter or restricted intake
- Fuel pressure regulator over-pressurizing fuel
- Leaking fuel injectors
- Faulty oxygen sensor or coolant temperature sensor
How to fix P0172
- Check and replace a clogged air filter
- Verify MAF sensor airflow readings against spec on an OBD-II scanner
- Test fuel pressure and check for injector leakage
- Monitor O2 sensor switching and fuel trims for confirmation
- Repair or replace the component causing over-fueling