Common Causes:
* Loose or damaged gas cap: This is often the simplest and cheapest fix. A loose or faulty gas cap can allow fuel vapors to escape, triggering the light.
* Oxygen sensor (O2 sensor) malfunction: This sensor monitors the oxygen levels in the exhaust and is crucial for proper fuel mixture. A failing sensor can cause poor fuel economy and emissions problems.
* Mass airflow sensor (MAF sensor) problem: This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor can lead to a rich or lean fuel mixture.
* Catalytic converter issues: A failing catalytic converter can cause reduced engine performance and trigger the engine light. This is usually a more expensive repair.
* Spark plugs or ignition coil problems: Worn-out spark plugs or a faulty ignition coil can cause misfires, leading to the engine light illuminating.
* PCV valve (Positive Crankcase Ventilation) failure: A clogged or malfunctioning PCV valve can cause excessive pressure buildup in the engine, leading to various issues.
* Throttle position sensor (TPS) malfunction: This sensor tells the engine control unit (ECU) the throttle's position. A faulty TPS can cause poor engine performance and the engine light to come on.
* Crankshaft position sensor (CKP sensor) or camshaft position sensor (CMP sensor) problems: These sensors are crucial for engine timing. A malfunction can cause the engine to run poorly or not at all.
Less Common but Still Possible Causes:
* Exhaust system leaks: Leaks in the exhaust system can affect the oxygen sensor readings.
* Problems with the engine control module (ECU): Although less frequent, the ECU itself can malfunction.
* Various sensors: There are many other sensors in the engine that can cause the light to come on if they fail.
What to Do:
1. Get the codes read: The most important step is to take your Cavalier to a mechanic or use an OBD-II scanner to read the diagnostic trouble codes (DTCs). These codes provide clues to the specific problem.
2. Don't ignore it: Driving with the engine light on can cause further damage and may lead to failing an emissions test.
3. Consider the symptoms: Note any other symptoms accompanying the engine light, such as rough idling, poor fuel economy, or loss of power. This information can help in diagnosing the problem.
In short, without knowing the specific DTCs, any answer would be pure speculation. A proper diagnostic scan is essential for accurate diagnosis and repair.
