2. Oxygen sensor issues. Oxygen sensors monitor the amount of oxygen in the exhaust stream and help the engine control unit (ECU) adjust the fuel mixture accordingly. If an oxygen sensor is faulty, it can cause the ECU to receive incorrect information and adjust the fuel mixture incorrectly, which can lead to a check engine light.
3. Spark plug wires issues. Spark plug wires are responsible for conducting electricity from the distributor to the spark plugs. If a spark plug wire is damaged or loose, it can cause the spark plugs to not fire properly, which can lead to a check engine light.
4. Mass airflow sensor issues. The mass airflow sensor measures the amount of air entering the engine and helps the ECU calculate the amount of fuel to inject. If the mass airflow sensor is faulty, it can cause the ECU to receive incorrect information and adjust the fuel mixture incorrectly, which can lead to a check engine light.
5. Catalytic converter issues. The catalytic converter is a device that helps convert harmful pollutants in the exhaust stream into less harmful substances. If the catalytic converter is damaged or clogged, it can cause the ECU to detect an increase in emissions and trigger the check engine light.
6. Evaporative emissions control system issues. The evaporative emissions control system (EVAP) is responsible for preventing fuel vapors from escaping into the atmosphere. If there is a leak in the EVAP system, it can cause the ECU to detect an increase in emissions and trigger the check engine light.
7. Engine coolant temperature sensor issues. The engine coolant temperature sensor monitors the temperature of the engine coolant and helps the ECU adjust the fuel mixture and ignition timing accordingly. If the engine coolant temperature sensor is faulty, it can cause the ECU to receive incorrect information and adjust the fuel mixture and ignition timing incorrectly, which can lead to a check engine light.
8. Knock sensor issues. Knock sensors detect the sound of engine knocking and help the ECU adjust the ignition timing to prevent knocking. If a knock sensor is faulty, it can cause the ECU to receive incorrect information and adjust the ignition timing incorrectly, which can lead to a check engine light.
9. Throttle position sensor issues. The throttle position sensor monitors the position of the throttle plate and helps the ECU control the fuel mixture and idle speed. If the throttle position sensor is faulty, it can cause the ECU to receive incorrect information and adjust the fuel mixture and idle speed incorrectly, which can lead to a check engine light.
10. Faulty ECU. In some cases, a check engine light malfunction can be caused by a faulty ECU. The ECU is the main control unit of the engine and is responsible for managing all of the engine's functions. If the ECU is faulty, it can cause the engine to run improperly and trigger the check engine light.
