I own a 2007 Land Rover Range Rover HSE. the coolant sprung a leak while on the highway and the temperature spiked. I pulled over right away and shut the engine off.

it was cold and raining. I didn’t see any coolant leak pooling on the pavement however.

while waiting for a tow, my windows got very foggy.

i wanted to just start the truck and quickly clear the damp air from the cabin. When I did, the temperature gauge showed normal.

i turned on the defrost to clear the cabin. That’s when the coolant temperature gauge started going DOWN! It went all the way to low without me touching anything or driving.

has anyone ever seen this before?

 

Maybe your thermostat is occasionally sticking. You could take it out and either test it or replace it and see if that takes care of it.