My car over heats when i take long rides. on 2005 Dodge Magnum

A red light comes on my dash and the temp gage dropps to cold. Whrn i stop or idle the car over heats. Ive tried to cut the car on and turn the a on and both fans are coming on.

Asked by for the 2005 Dodge Magnum
2 answers 1 comment
maybe the fan is not turning on early enough
Also when i cut the car off and restart. The light gos off and the temp gage start back working. It only over heats on long tripps.
if your fans are working you could have a bad t stat