My check engine light recently came on and I took it to AutoZone since they will pull the code for free. They told me it was the gas cap. I had my car in for a oil change and had the dealer pull the CEL error code, for free, which shocked me. They said it was some kind of valve timig issue and that it wouldn't leave me stranded, but my question is damage to the engine. The error code as PO457 and I can't find anything on it. Has anyone had this before and what does it stand for? The car is bone stock and has 36,400 miles on it. Any feed back would be appreciated.