What can cause a check engine light?

Some common causes of the check engine light turning on include:

• Loose or faulty gas cap: A loose or faulty gas cap can cause the check engine light to come on because the OBD system detects a leak in the evaporative emissions control system.
• Oxygen sensor: The oxygen sensor is responsible for measuring the amount of oxygen in the exhaust and sending this information to the engine control module (ECM). When the sensor fails or becomes worn, the check engine light will come on.
• Catalytic converter: The catalytic converter is an emissions control device that converts harmful pollutants in the exhaust into less harmful gases. If the converter becomes clogged or damaged, the check engine light will come on.
• Mass air flow sensor: The mass air flow sensor measures the amount of air entering the engine and sends this information to the ECM. When the sensor fails or becomes dirty, the check engine light will come on.
• Ignition coils and spark plugs: Ignition coils and spark plugs are responsible for providing the spark that ignites the fuel in the engine. When these components wear out or fail, the check engine light will come on.