i just bought a used mustang, 37k miles on it, that was yesterday. Tonight, at 11pm, too late to call the dealer, I got a Service ENgine SOon light that popped up out of nowhere while gettin on the freeway. I'm freaking out, I don't know what it is, and I don't know how I could have gotten that. The car is running perfectly fine, but I'm scared. Could someone please give advice on what causes that light to pop up? I turned it off and on and it remains constant. :-?