P0172
System too rich (Bank 1)
Fuel-trim monitoring indicates that Bank 1 is running richer than the ECU can correct within its normal range.
What this code means
Fuel-trim monitoring indicates that Bank 1 is running richer than the ECU can correct within its normal range.
Possible causes
- Excess fuel delivery
- Restricted air supply
- Faulty air-flow or pressure sensor
- Leaking fuel injector
- Incorrect fuel-pressure regulation
- Oxygen sensor or related feedback fault
Common symptoms
- Check engine light
- Poor fuel economy
- Rough running
- Fuel smell or dark exhaust in some cases
Checks to make
- Check for related fuel-trim and sensor codes
- Inspect the intake and air filter
- Review short- and long-term fuel trims
- Check fuel pressure and injector operation as appropriate
Safety
- Fuel systems can remain pressurised after the engine is switched off. Follow manufacturer procedures before opening the fuel system.
Model notes
Bank 1 is the cylinder bank containing cylinder 1.