To find out why the light is on, you'll need to:
* Check for a loose gas cap: This is the most common, and easiest, cause. A loose or damaged gas cap can trigger the light due to evaporative emissions system issues. Tighten it securely and see if the light goes off after a few drive cycles (start and stop the car a few times).
* Obtain a trouble code: Even though it's an OBD I system, a code is still stored. You'll need a code reader specifically designed for OBD I (often called a "backprobe" or "jumper wire" method) to retrieve the diagnostic trouble codes (DTCs). Auto parts stores often have these readers or can read the code for you. Some mechanics can also diagnose the problem without a reader using a multimeter.
* Consider common issues for a car of that age: Given the age of the vehicle, the problem could stem from various things including:
* Oxygen sensor: A failing oxygen sensor is a frequent culprit.
* Mass airflow sensor (MAF): This sensor measures the amount of air entering the engine.
* Throttle position sensor (TPS): This sensor informs the engine control unit (ECU) about the throttle position.
* Catalytic converter: A failing catalytic converter can trigger the SES light.
* Ignition system problems: Issues like faulty spark plugs, wires, distributor cap, or rotor.
* Vacuum leaks: Leaks in the vacuum system can disrupt engine performance.
Without a trouble code or further diagnostics, pinpointing the exact cause is impossible. A mechanic familiar with OBD I systems will be best equipped to diagnose and repair the underlying problem. Trying to fix it without knowing the cause might lead to further damage or wasted money on unnecessary parts.
