Now what? I put the cap back on two days ago but the CEL hasn't disappeared? I was told it would.

 

Reset your computer.

 

It takes several days. The car will need to be driven for an extended period several times for it to go away. Short trips do not count if the car does not fully warm up. You did check the CEL code to make sure it was the gas cap CEL didn't you?

 

When I first got my car, the dealership filled it up for me and didn't put the cap on properly... before I even had a chance to fill up the car I had that damm msg. I think I drove for over two weeks and 800miles w/ the light... I talked to the dealer and it went away on its own eventually... just might take a while.