So I am a bit lost right now as to how to approach this issue. I have been having trouble lately with fuel cap. Old one seem to just not function properly anymore and was getting codes for fuel system. got a correct chev cap for it and still coding car, and will put into limp mode. I do not believe it is a sender problem as I currently have a rag over new gas cap and car works perfectly with the rag. What should I be chasing to solve this problem.