I'm assuming your car is brand new from the dealership and is still under warranty. Have you done any mods to it? If not take it to the dealership and have the service guy read the code real quick and he can usually fix you up under warranty. If you've done some kind of mod that might of had some effect, take it to autozone, orielys, or some other parts place and have them read the code. They'll do it for free. Then come back here and tell us the code. And yeah... what gas cap?