external temperature sensor showing --°C

hello

I have problem with displaying external temperature on display.

car is 2004 C2. It had only clock , no multifunction display. So I made a loom , installed multifunction display "B" , changed mirror for mirror with temperature sensor, configured via Lexia but display show only " --°C " , no values from sensor. is sensor faulty ? or I forgot to configure something?

thanks for your replies

The external sensor goes straight to the BSI.
The sensor is just a resistor that changes it's value with temperature.
You could try shorting out the connections at the door loom connector or substituting a resistor value. It's about 4K Ohms. It might not read anything if you short it out, but I don't know.
If you get any kind of change in the display then you know the sensor is the problem. If you don't then its the wiring or the configuration.

thanks, I will check the sensor , or will try another mirror with sensor