Today i was driving and my temperature gauge is normally stuck on cold. It never comes off of cold, so i figured it was just stuck. Well today, out of nowhere the temperature gauge shoots up to HOT. I pulled over and waited for about only 2 minutes and i opened up the radiator top and nothing was happening in there. Nothing was bubbling out. Do you guys think maybe my temp gauge is just broke or maybe i might need a new thermostat? Thanks for any help!!

 

Here's a wild guess: The temp sender wire has been off of the sender (that's why it didn't move), and sitting on the exhaust manifold. Today, it finally melted through the insulation and the wire shorted to the manifold (that's why it shot up to hot).