I had a lot of repairs done about 2 mo. ago on the fuel emssions system and computer replaced, and throttle body replaced. When I was driving it home, I noticed the low coolant light on. I took it back to have coolant checked, it was fine so I went ahead and had it replaced. It would always come on after I drove it for awhile. Air worked without overheating, heater worked, and the gage seemed to work ok, mark just below half way mark. The light would come on almost as soon as I hit close to the same mark. The computer was reset hopefully right. I'm out of ideas.