Yep!
Mine was turned off this morning for the first time after buying the car.
In my case the ecu was screwed. It had a hole in it and severe corrosion to the circuit board itself.
Before determining this was the cause and searching for one on ebay, I did research to determine if I could diagnose it. Typically the problems that cause the fault you mention are corrosion of the pins inside the multiplug that connects to the haldex ecu itself, and corrosion of the earth point of the loom which is attached to the rear subframe.
Check these first. If it these don't solve it, you are probably best off just replacing the ecu like I did.
You then need to determine if you have a gen 2 or gen 4 ecu. This is determined by the age of the car. Pre 8p3 they were gen 2. This is the same as the mk2 TT and the Golf mk5 4 motion or R32. If your car is pre 2008, it is likely to be gen 2. You can determine for sure by reading the code on the bottom of the haldex diff unit. If it is OAV it is gen 2. If its anything else it is gen 4 (there are three options I think one of which I recall is OBV but can't remember the others ).
The gen 2 and gen 4 Haldex ecus look identical to one another, but they differ in firmware and cannot be interchanged.
FYI gen 3 was reserved for some and saabs.
If looking on ebay try to pay under £200. Most sellers don't list them separately and sell them with a complete rear diff. Search for golf, quattro or TT rear diff.
Took me ages to sort this out, but got there in the end. The part from audi was £800. I also tried people who had upgraded to the performance haldex controller but never managed to find any or at least not from the correct gen diff.
Hope this helps.
Good luck with your search!
