My ML500 is throwing a CEL since about a day ago. The car has been making some funny smells, almost like when a car is overheating, but not as strong. Its not overheating at all though. I get the wiff of it every once and a while. Then the truck threw a CEL and thats where its at now. When I do start the truck, however, the CEL comes and stays on and where the mileage reads it shows the service wrench and says 1000, but that wouldn't be the reason it would throw a CEL. I've been using regular gas, thats the only faulty thing i can think of. Anyone have any ideas?