The mixture on bank 1 has too much fuel or too little air. The driver may notice high consumption, a fuel smell from the exhaust or black smoke.
Likely causes, most common first
- Leaking fuel injector
- Excessive fuel pressure
- Dirty or faulty MAF sensor
- Saturated EVAP purge or clogged air filter
Parts usually involved
- Fuel injectors
- Fuel pressure regulator
- MAF sensor
- Air filter
Test before you replace
Check fuel trims, fuel pressure and the purge valve, and look for leaking injectors before replacing a sensor.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.