250k miles 2013 malibu Lt took a few hours but just finished replacing both rear hubs. went for a test drive, before I pulled off to drive, the display warns me of overheating engine and the temp needle is pinned to the hot side of the gauge. both fans are running full-on. the engine is not even warm yet. no leaks, coolant in the system I can put my hand on the radiator hose cool to the touch. never had this happened before, is there a glitch? I waited a few minutes later to check like 10 minutes later and the needle was back to normal as well as the display. I drove for a few miles with no problem so far, but then the temp needle was bouncing around between norm and close to the hot side. weird I put my hand on the rad hose without burning myself temp seems normal to me. I was told to flash the computer to reset the sensors. what gives.