1999 passat temperature gauge

My Passat's temperature gauge has been going up and down during my commute the past few days. It rises to it's normal temp, which is straight up at 190, and then will go all the way to cold every now and then. It never runs any hotter than normal. The car seems to be running fine. The A/C works fine. Nothing leaking from the radiator.

It's a '99 4 cylinder turbo with 68000 miles on the odometer.

Is it the thermostat? Thanks for any advice.

I was having the same probelm with my 00 v6.
It was the temperture sensor. My mechanic explained that over time deposits in the coolant build up on the temperature sensor and give you false readings. Mine would be all over the place 96 one minute 190 the next. Flushing the cooling system and replacing the sensor should do the trick.
Good Luck.

I have the same excact problem with with george100 in my 2000 passat.feels like it happens when i use the ac..i was wondering if you solved the problem. I would appriciate it if you let me know if that was the sensor.
Thank you
Arky