Nothin major... I got a CEL about a month ago, car was still running for a week.. then had starting problems and really bad idle. I couldn't for the life of me, find what the problem was. After spending quite a bit on un-necesarry maintanence. I finally decided to stop being stubborn and borrowed a OBD-II scanner from a tech at work. found out all my problems were from two things: O2 sensor and IAT sensor... son'ova'b! located the sensors and made sure they were secure... fixed my problems! dammit, wasted money and time on sh!t I didn't need to do...

So lesson learned... use a damn scanner next time you have a CEL.