The check engine light keeps coming on - about 2 years. Each time the computer reading is different. They never find something wrong. The time between is a few days to months. Some times they just turn it off, some times it goes off on by itself before I get to the scheduled appointment. The lead mechanic has been working on this to no charge to me. This last time it said the fuel was low. (Not true.) I have not taken it to a dealership because I have always been pleased with this business. Also It now just developed a new trick, heat comes through the vents with it not being turned on - the engine is not over heating. I assume that is just a switch.
That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.