Mitsubishi Repair: service engine soon, advanced auto parts, modern cars

Question
I have a 2002 Galant GTZ.

Would you happen to have a list of possible reasons that could cause the "SERVICE ENGINE SOON" light to turn on? Maybe some things I could check myself since my warranty just ended.

Thanks a lot

Answer
Eddie,
There are more causes for the check engine light to come on in modern cars than I could even list.  But typically it will come on due to an emissions, ignition, or timing problem.  Even something as simply as your gas cap being screwed on too loosely will cause the 'service engine soon' light to come on.  If your car appears to be running fine but the service engine light remains on, it's probably an emission problem.

If you have an AutoZone store in your area, you can take you car there and tell them your check engine light is on.  They will be able to hook up a code reader and tell you what's causing it to be on.  Best yet, this is free!  Other parts stores like PepBoys and Advanced Auto Parts may also provide this as a free service as well, but it's best to check with them first.  Else, most local mechanics have code readers that will be able to read your car's computer for trouble codes.
Good luck!