- The gas cap may not be tightened enough. Make sure that the gas cap is tightened until it clicks three times.
- The gas cap may be damaged. If the gas cap is cracked, broken, or otherwise damaged, it may not be able to seal the fuel tank properly.
- The EVAP system may be faulty. The EVAP (evaporative emissions) system is responsible for preventing fuel vapors from escaping from the fuel tank. If any component of the EVAP system is faulty, it can cause the check engine light to come on.
To diagnose the problem, you can:
- Check the gas cap. Make sure that the gas cap is tightened until it clicks three times. If the gas cap is damaged, replace it.
- Check the EVAP system. You can check the EVAP system by performing a smoke test. A smoke test will reveal any leaks in the EVAP system.
- Have the car diagnosed by a mechanic. If you are not able to diagnose the problem yourself, you can take the car to a mechanic. The mechanic will be able to use a diagnostic tool to identify the source of the problem.
Once the problem has been diagnosed, you can repair it and the check engine light will go out.
