Here are your options:
* OBD-II Scanner: The most reliable way to diagnose the problem is with an OBD-II scanner. These are relatively inexpensive and can be purchased at most auto parts stores. The scanner will read the DTCs, which are numerical codes corresponding to specific problems. You can then look up the codes online or in a repair manual to understand what's wrong.
* Auto Parts Store: Many auto parts stores offer free diagnostic code reading services. They'll plug in a scanner, tell you the code(s), and might even offer suggestions, though their recommendations may be biased towards selling you parts.
* Mechanic: A qualified mechanic will have the tools and expertise to diagnose the problem accurately and perform the necessary repairs. This is generally the most expensive option, but it's also the most reliable.
Possible Causes (without knowing the DTCs, this is pure speculation):
The SES light on a vehicle this old could be triggered by something minor (like a loose gas cap) or something serious (like a failing catalytic converter or oxygen sensor). Some common possibilities include:
* Loose or damaged gas cap: This is the easiest and cheapest thing to check first. Make sure your gas cap is securely tightened.
* Oxygen sensor: A malfunctioning oxygen sensor can affect fuel efficiency and emissions.
* Mass airflow sensor (MAF sensor): This sensor measures the amount of air entering the engine and a faulty one can lead to poor performance and the SES light.
* Catalytic converter: A failing catalytic converter can be expensive to replace.
* Ignition system problems: Issues with spark plugs, wires, or the distributor (if applicable) can trigger the light.
* Other sensors: Various other sensors throughout the engine and emissions system can trigger the light.
Do NOT ignore the SES light. Driving with a problem can lead to further damage and potentially unsafe driving conditions. Get the codes read as soon as possible to determine the cause and get it fixed.
