- Vacuum leak: A vacuum leak can cause the engine to run lean by allowing unmetered air to enter the engine. Check all vacuum lines for cracks or leaks and replace any that are damaged.
- Faulty oxygen sensor: The oxygen sensor measures the amount of oxygen in the exhaust gas and sends this information to the ECU, which adjusts the fuel mixture accordingly. A faulty oxygen sensor can cause the ECU to run the engine lean. Test the oxygen sensor and replace it if it is faulty.
- Dirty fuel injectors: Dirty fuel injectors can cause the engine to run lean by not delivering enough fuel to the cylinders. Clean the fuel injectors or have them professionally cleaned.
- Clogged fuel filter: A clogged fuel filter can restrict the flow of fuel to the engine, causing the engine to run lean. Replace the fuel filter if it is clogged.
- Incorrect fuel pressure: Incorrect fuel pressure can cause the engine to run lean by not delivering enough fuel to the injectors. Check the fuel pressure and adjust it if necessary.
