Okay so for the first time since I've owned this car, which is about 100,000 miles, I am getting the SES light. The engine appears to be running just fine, I know in some cars an old Cat. would throw this code, or could it be I just need new plugs? I really haven't had time to look too much into this problem, all I know is that the engine is still running fine. Obviously new plugs and wires would be a cheaper route, I'd hate to bring it to the garage to get a computer diagnosis if I don't have to.