I have problem with my Fiesta MK4 1.25 16V 1998. My temperature gauge read cold only when car is 100% cold. After 5 minutes of engine working my gauge go from cold to hot in couple of seconds. Changed engine coolant temperature sensor, changed gauge... But problem is still here.
On video I show moment when it go from below cold to hot. Before that car was working 4-5 minutes.
https://youtu.be/SOHtBMb32vQ