My 2011 3500HD popped this message up on the DIC today "Engine hot, air conditioner off" and I noticed my temperature gauge was not reading, its needle didn't move off of 160 degrees. I stopped by the dealer and they said its more than likely the thermostat and they will fix it Thursday morning. Does this sound right? Truck is not over heating as far as I can tell. Dealer didn't seem to concerned. If it is the thermostat, does anyone know if this falls under the powertrain warranty? If not I was going to change it myself.