The temp gage on my wife's Malibu stopped working yesterday. She called me at work and told me it hasn't moved after driving for an hour. I told her to turn off the AC and turn on the heater and she was getting heat then I told her to pull it over and check the coolant. Coolant was fine and no water in the oil. She went to start it back up and it ran really rough so she shut it off but it wouldn't start again. I left work and it took me an hour and a half to get where she was and when I got there it started right up. I called the dealership where we got it (December) and found the warranty was over but he did tell me that the sending unit goes to the ecm then to the throttle body and a few other places. Car runs fine, gage doesn't work.

Same thing happened to mine, except when I pulled over to check the same thing your wife did and I restarded the vehicle the gauge was working fine and has ever since, we have a fleet of vehicles where I work and 3 out of the dozen or so we have have done that in the past.

The gage started working fine today.