Check engine light is a way for car's computer (ECU) to signal "something" is wrong. You would think in modern day of cheap LCD they could do better.So instead of guessing, go to AutoZone and they'll scan the computer and look for a code (ODB II connection). The code are very specific (some times getting down to the exact engine cylinder for misfires) and it will give you very good information. But be warned that just because it mentions a specific engine part (like Oxygen sensor) that may not be the part at fault (but most of the time it is).Modern cars give off check engine light often. You can even get check engine light if you don't tighten gas caps, oil filler caps or dip sticks. So it would be a good idea to get a ODB II scanner ( they could be had as little as $50 on sale at sears or AutoZone, if you get lucky). Besides one scanner could be used for multiple cars (yours, brother's, sister's, mom's, etc.)