check engine light comes on after riding at 55 mph

Hello, This is most likely an oxygen sensor problem, although there is no way to be sure until you have the codes checked. The check engine light indicates there is a malfunction in the engine management system. A fault code will be stored, and someone with the proper equipment to read it (such as a mechanic) can give you an exact diagnosis. Don't worry though - an oxygen sensor should cost less than $100 to fix if that turns out to be the problem. Best of luck! CarGrrl