Originally Posted by Display_Name
(This has nothing to do with the check engine light, but it might explain why the fuel door doesn't close.)
Sometimes the "lanyard" that hooks the gas cap to the car gets twisted up a bit and when not folding down correctly it interferes with the hinge of the fuel door, making it so the fuel door doesn't close down all the way.
Thanks, I will go out and check that. Hope that does the trick if it lays out of the way of the closing.