Possible causes are extremely varied and range from something minor (like a loose gas cap) to something serious (like a failing catalytic converter).
To find out what's causing the light:
1. Get the diagnostic trouble codes (DTCs): You'll need an OBD-II scanner to read the codes stored by the car's computer. Auto parts stores often offer free code reading services. The codes will give you a much better indication of the problem.
2. Consult a repair manual: Once you have the codes, a repair manual specific to your 1998 Mercury Sable can help you understand what the codes mean and how to address the issue.
3. Take it to a mechanic: If you're not comfortable diagnosing and fixing car problems yourself, a qualified mechanic can diagnose the problem and make the necessary repairs.
Ignoring the service engine light could lead to further damage to your vehicle or even safety issues. It's best to address it promptly.
