To my knowledge, the check engine light isn't used as a maintenance reminder on these. The check engine light is there so the computer can tell you that it sees some fault. The first step in diagnosing this is to get the trouble codes from the computer. If you don't have a code reader/scanner of your own, then you need to find one. Some parts stores will read trouble codes for free, in the hopes of selling you something. Even if you choose to have the dealership do the diagnosis for you, knowing the trouble codes before you take it in will help you go in with your "eyes open."