Check Engine Light

I have a 2001 Jetta and about 3 weeks ago I replaced my brake light switch and temperture sensor due to EPC light coming on and off, then finally stayed on. Well now my check engine light came on any suggestions on what this can be. I know you can have the codes read at autozone and pep boys, and etc. Just thought someone else has had the same probs.

Nothing feels different on driving nor any other probs. for now. Please help.
thanks
HRstein1

Just go in and ask if they can scan the engine computer for codes.