'Last week, I took my TDI to the TÜV (German technical inspection agency). During the inspection, they also checked the engine control unit. I think they were trying to see if there was a tuning box or something similar hidden inside, or whether it had been opened before (is that even visible?).'
"Um genau zu sein, was meinst du mit 'kann man das von außen sehen?' - Nein, because it would really take someone to make deep scratches into the control unit with a screwdriver for it to be noticeable on the housing. Unless, of course, some tuner has stuck a large sticker onto the control unit!"
You can see such an intermediary if you look closely!
He removed the rubber seal in the middle, near the windshield wipers. I can't imagine he did it to better see the vehicle identification number, since there's a viewing window for that. Then, he shone a flashlight inside and seemed to be poking around. It just occurred to me that maybe he was looking at the control unit (ECU)!
He compared the vehicle identification number with mine. Can you actually see the control unit through the viewing window? It's a small, silver (sometimes black) box.