7k on my base rsx, my check engine light just came on.
Bone stock engine with type-s comptech shorty header, type-s cat (stock 02 sensors), type-s cat-back exhaust. I'll most likely have to bring it to the dealer to decode but i know they will blame it on my mods & make me pay. Can those above parts throw me a CEL? I just tightened the gas cap but i doubt that's the problem.

 

Possible that the Type S cat is throwing a CEL, but you really won't know anything until you get the code read (even Autozone or a local shop will do that for you for free). If you take it to the dealer, just have them read/clear the code. They shouldn't charge for that.
Then, post the code (or look it up) and go from there.