Temperature Overload???

[bmann]

The current temperature in Winnipeg Canada is -35 (with the windchill) Anyway, I was driving when all of a sudden, the temperature needle pinned to the right. the red hot light indicator did not come on nor did the check engine light. I pulled over, turned the vehicle off, checked the coolant level (it was fine) and restarted the vehicle and everything worked fine. The engine did not seem to be overheating. When I got home, I connected my Peak FCXII. It did come up with this... "coolant temp too low for closed loop operation". I believe this has something to do with the thermostat?? Can anyone verify this and if so, please let me know if this is a major item to repair??? Is it a possible do it yourself item? Is there a diagram of the repair? Thanks