● Fix soon
Usually drivable for a short time, but check it soon. It can get worse.
Usually drivable for a short time, but check it soon. It can get worse.
The mixture on bank 1 has too much air or too little fuel, and the computer has reached its correction limit. The driver may notice hesitation, rough idle or nothing beyond the engine light.
Guided check
- Do you find a vacuum leak (hose, intake gasket) with a smoke test?If yes: Repair the leak, clear the code and check fuel trims again.
- Is the air flow (MAF) reading low for the engine size or the sensor dirty?If yes: Clean the sensor with MAF cleaner and test again. Replace it only if the reading stays wrong.
- Is the fuel pressure below the maker's value?If yes: Check the fuel filter and pump, and the regulator where fitted.
These checks are general and are still being reviewed by working mechanics.
Causes vary by car. Test before you order a part.
Likely causes, most common first
- Vacuum leak after the air flow sensor
- Dirty or faulty MAF sensor
- Low fuel pressure
- Exhaust leak before the oxygen sensor
Parts usually involved
- Intake hoses and gaskets Find at suppliers
- MAF sensor Find at suppliers
- Fuel pump Find at suppliers
- Fuel filter Find at suppliers
Test before you replace
Compare fuel trims at idle and at 2500 rpm, smoke test the intake and measure fuel pressure.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.