Check engine light - 2000 SS

Hi, I have a 2000 Monte Carlo SS and I love it and have had no problems at all except for one - The check engine light has been on for awhile. It's been to the shop twice for the problem and both times they said it was the gas cap which I replaced and the light stayed off for awhile but always comes back. Has anybody else had this problem, and am I looking at some major repair bill here? Car has 48000 miles on it and in excellent shape otherwise.

I also had that problem (2001 SS), but after taking it to the dealer twice in 3 months, all they could tell me was that my gas cap was loose. I know that was not the case, and taking it to the dealer became a pain in the neck, so I went to my local auto parts store and purchased an OBD II code reader. Now I can read the trouble codes myself, and reset the Check Engine light.