New thermostat/temp sensor needed?

It's -20C and colder here for the last 2 days and I've really started to notice my that my Golf struggles to maintain it's temperature.

I know the needle is nowhere near accurate but if I let the engine get to heat while I drive with the dial all the way to cold, once I turn it to heat the gauge will drop with a fan speed higher than 1. At lights the gauge drops and if I leave the car running while sitting for a bit it will go to about half-way to running temp. The heat doesn't blow that how either.

I've heard that this issue is more related to the thermostat rather than the coolant sensor.

Thank you

It could well be. My thermostat was opening at 80 degrees C and after replacement, the coolant registered 89.1 degrees C, as determined by logging coolant temperature for a 40 minute higway drive, using my VCDS and a laptop before and after thermostat change. The coolant temperature sensor was believed to be accurate since it was a VW one and about two years old.

You may also want to block the front grills. That may help. But at the temperature you mention (-4 degrees F), what you describe probably is normal. Coldest I have driven mine is at about 15 degrees F. and when the car as new, the temperature gauge would fall when I began driving slow in 15 degree weather.

--Nate

I've covered up the the bottom and top grill with pipe insulation.