Ok, i know that there are other threads on this, but what would all the causes be for this to come on. My jeep was running fine 2 days ago, then shortly after i started it today the ligt came on. Everything sounds and ran fine, i dont have a temp gauge or tac so the only way that i know if my temps are wrong is if it over heats. I am in Vermont right now and i have a feeling that the cold has something to do with this. It is a '98 4.0.