This has been driving me mad for the last 2 months!! I retrofitted cruise control (2009 s3 stronic facelift) no probs. the steering wheel coded fine and diag shows all buttons working ok.
The problem is the engine coding. Setting the cruise control bit just doesn't seem to take. I've tried doing them in different orders, ignition off and on, ignition left off and the apparently sometimes needed TBA. It says coding accepted, but then it just doesn't work. When I reopen the coding the bit is unset again, even after all the things above. It's really weird. Just wondered if anyone had seen anything similar.
I should say this is not a genuine cable in use. If people have seen issues like this I guess it would be a good reason for buying the proper one!