VW Polo 9n (eyepiece) 2002 1.4 TDI 75KM - coolant fluid indicator

Hello, for some time I have had a problem with the coolant indicator light coming on in my Polo.
Searching the Internet I did not find an identical problem (similar problems and their solutions do not work).
This light comes on most often after the engine is warmed up, the pointer normally travels to around 90 degrees Celsius and keeps the temperature while driving, although it happened that it came on immediately after leaving the garage. I will add that the computer does not see any errors ...
I started by replacing the coolant tank, first used then a new replacement together with the liquid. No results, I replaced the thermostat did not give anything, someone suggested replacing the engine temperature sensor or the coolant temperature - I replaced both and nothing ... Time to check the installation, therefore I have a question if anyone has a diagram that matches this problem?
Or maybe someone has an idea what could be the reason?

If someone has a similar problem, the meter was to blame for me

Hello, I have a similar problem, so yes, at the beginning it started with a problem with the immobilizer, the indicator light from it blinks and after firing the car goes out. I read a bit on the forum and someone advised to hit the counter (I was surprised that such simple methods can work) after hitting the counter, the indicator disappears and the car fires normally. Now the airbag indicator is on all the time, and the coolant temperature indicator blinks after 5 minutes of driving and so on all the time. A familiar electrician told me that the meter is cold February and after soldering the cables it should be okay. And my question is, has anyone done such an operation on the counter and does it help ??

The meter is done, everything as it should be, also if someone has problems in the car with the controls, the pins on the meter are loosened and you need to re-solder.