Engine temperature sensor

Hello, I haven’t been in touch for a long time – just because the thickness purrs without any problems. But now he has to go to TÜV. Had the hand brake set short, because on the right no effect. Thought, now everything is good. Because. AU did not pass. Value 3,9. I searched the forum and found the “motor temperature sensor”. Now my question: Under what do I find the one at Skandix? (or else where?). Because there are a lot of donors, for oil, for water…. Which one is it? (Is it?) The one who sits under the thermostat, which I had already exchanged?) Because I also need the contact plate. It only works every 10th time, but of all times at the TÜV. I meant “ABS system….kaputt”. That a little turning back of the key helps, I didn’t want to tell him, because for safety I build a new one. As said, again asked: What is the name of this MTG exactly? Otherwise everything was great, the examiner was very enthusiastic about the substructure. All top. Data: 850, 144 HP, over 300 TKm (Tac Ho broken), Ez 03/95. Driving mainly: 2 times daily 12 km pure highway, 2 times weekly 25 km city/road, always cruising, always in 5th gear, never over 3000 tours, consumption 9.5 liters Prophylactically also the Lambda exchange? I hope not that the cat is over…… And thank you.