Liebherr fridge freezer CNel4213, index 21f/147 problem

Have a customer with the above f/f that has wild temperature fluctuations on fridge and freezer. Both intermittently are warming beyond their normal ranges and setting off alarms and then settling after a few hours. I’ve read various posts on Liebherr fridge freezer faults and they mostly seem to lead to the evaporator sensor which I’ve ordered. When I come to replace it, in the fridge is a red marked air sensor(?) and behind the cover is a green marked loop of wire but no sensor showing. Is the sensor foamed in or does the loop pull out to reveal a sensor? Any help appreciated as I’m at a complete loss with the Liebherr stuff but feel I need to give it a go as we sell the stuff.

Cheers

Tony