A couple of years ago,the electrics on my b5 passat started playing up,central locking/windows etc.
Looked into the problem and found the CCM under about 2 inches of water.(it sits under the carpet on the floor!)
Well known problem with the passat so no need to go into detail about the cause. Two of the pins on the ccm socket had corroded and broken off so purchased a second hand one with all the numbers matching which came with some of the wiring so repaired some of the crusty wiring on the car with that.S/hand ccm fitted and all working again,or so I thought.
Doing a vagcom scan last week "no alarm/immobiliser installed" Checked the coding and can't see any option to enabled this.? So bought another cheap ccm and removed the socket and re-soldered on to the original ccm and fitted it back in the car and "bingo" all working .The reason for the 3rd one is I did not trust my soldering skills and didn't want to bugger up the working one!
The point of this is although the part No's match it seems the software might not match exactly.
Don't know if it applies to any others (TTs?) but might be worth bearing in mind .