The mixture on bank 2 has too much air or too little fuel, and the computer has reached its correction limit. The driver may notice hesitation, rough idle or only the engine light.
Likely causes, most common first
- Vacuum leak on the intake or bank 2 side
- Dirty or faulty MAF sensor
- Low fuel pressure
- Exhaust leak before the bank 2 oxygen sensor
Parts usually involved
- Intake hoses and gaskets
- MAF sensor
- Fuel pump
- Fuel filter
Test before you replace
If both banks show lean, look first at air metering and fuel pressure, and smoke test the intake.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.