VW Golf 4 MKIV temperature error - [Solved]

Описание

Hi Youtube
Regarding my Volksvagon Golf MK4 from 1999.
I have a temperature error. Even after a 30 km ride, the in dash thermometer shows only 60-70 degrees, even though i should be hotter. If I turn the motor off, and put the ignition back on, the reading increases. Usually to around the expected 90 degrees, but in this video only 80 degrees.
I have checked the coolant and there are plenty. The temperature gauge have just been replaced, The old one did exactly the same (the reason i changed it) but the guage was apparently not the issue. Apart from this, the car is running as it should be, but I would like a trustworthy temperatur reading.
Any help on how to fix this, would be highly appreciated.
Cheers ;)