when it has been running for at least 5 min.then it will suddenly go to hot and the check gage light appears.then i have to turn my heat on to cool it down
my thermostat gauge is reading very cool. on 2001 Ford Ranger
The first thing to check is to see if it has any coolant in the radiator. If there is no coolant the coolant sensor will not register on the dash gauge. If it's full of coolant I would monitor the thermostat to see when it opens. A sticking thermostat, or one that opens at the wrong time could cause this issue.