Check engine light on 03 Tib GT

hey everyone well my check engine light is on. but the car is running perfectly fine. so i was just wondering could this just be a sensor or how bad could it really be. im going to the dealer tomorrow morning to get it looked at. i just want to know what you guys think it could be. thanks alot for any info

Without knowing the code, it could be anything. Get it scaned.

Without knowing the code, it could be anything. Get it scaned.
got it fixed all it was was that the gas cap was bad and it made the light go on. no charge at all for it and a free wash too

If you don't thighten the gas cap at least 3 clicks, it will throw a CEL.

got it fixed all it was was that the gas cap was bad and it made the light go on. no charge at all for it and a free wash too

same thing happend to my brothers rav4, he didnt tighten the cap enough so he went to the dealer and they charged him 80$ to tighen a cap and tell him what was wrong with it. stupid toyota <_<