2001 Jetta w/ Check Engine Light

Ugh, this damn car. OK, I have a 2001 Jetta, 65000 miles. Check Engine light came one for a day and a half last week and then went away. Now, yesterday, It was fine in the morning, stopped for lunch for an hour, and when I returned from lunch the light went back on. Any clues before I get charged way too much for a plug or something? I asked a Q last year about my blinker and was saved $100 buck thanks to suggestions from other readers.

If you have an Autozone or Advance Auto Parts store they can read the codes for you (even if the light happens to be out at the moment), usually for free.