Same as P0171 for Bank 2. Often appears together with P0171, pointing to a shared/global cause such as the MAF, fuel pressure, or a large vacuum leak.
SYMPTOMS
- Check-engine light
- Rough idle
- Hesitation
- Slight power loss
LIKELY CAUSES
- Vacuum/intake leak
- Dirty or failing MAF
- Low fuel pressure
- Dirty injectors
DIAGNOSIS STEPS
- Read fuel trims on both banks
- Smoke-test the intake
- Check MAF reading
- Verify fuel pressure
RELATED PARTS
- MAF sensor
- Intake gaskets/boots
- Fuel pump