WEIRD - Temp Gauge

My car stalled tonight and the temperature was fine, about 150-160. When I turned off the key after it stalled the temp gauge shot up to way past the red, almost couldn't even see the pointer. Turned the key to the on position and it went back to where it was. Did this everytime i switch on and off. It was reallly weird! Any idea why it would do this??

why did the car stall? user error or could it not keep itself running due to suffocation or fuel shortage?

When the motor is not running, the coolant is not circulating and therefore not disapating the heat. This is called hot soak and is normal. When you started the motor, cooler coolant was circulated through the motor.

You can check the temp sensor. Make sure it really is hot before coming to a conclusion and not a malfunctioning guage. I'd make sure the coolant is being circulated by the water pump and the thermostat is working properly. If the obvious is working then something electrical may be happening, but I tend to lean toward part malfunctions, i.e. coolant temp sensor, thermostat, water pump, fan relay(be sure fan is working) etc etc.

Hope this helps for you,
Mike

i noticed that it only does it with the headlights on... when i turn them off it goes back to normal

what year is your vehicle? i would guess bad thermostat which is easy to replace as long as you don' thave the stupid aluminum mounted one that is almost impossible too get out after being in for years of fusing. otherwise with your headlight theory you have a short somewhere causing your meter to misread and if you have a newer car the computer may have an automated safety feature to shut down the car at critical temps.