Hi there, I'm new to the forum and would be very grateful for some advice from you guys much smarter than me! Is it possible to reprogram a second hand ABS control module on a B9 A4? Here's the waffle as to why I'm asking: I have a 2016 A4 Avant Diesel 2.0 TDI 190. It recently showed the dashboard error "Brake servo: restricted. You can continue driving. Please contact workshop." So I took it to the dealer expecting to replace the pressure sensor (thanks to some research on this site) - hoping it's a £250 ish job. I then got following back from the main dealer: Event entry C123EF0 hydraulic brake servo limit reached is logged in the brakes control unit and the brake control unit is permanently deactivated. After testing, it is confirmed that a complete ABS control unit (J104) and hydraulic part must be replaced. The quote was a bit of a shock. This unit alone is apparently £2000. Presumably because they'd tried to clear the codes, the dasboard now shows "brakes: error. Please stop safely". Different to when I took it in. I bought a second hand module, all compatible numbers, model, revision etc. Confirmed as tested and working. Took it to my local independent who kindly offered to fit the part I supplied. They has suspicion that the ABS unit on this model has a one-time programmable VIN entry. So you can't swap ABS units between cars. I've attached a screenshot of the error they get when trying to program the controller. So basically, is this really true? Is it impossible to reprogram the VIN on an ABS module and fit a used part? Sorry for the long thread. Any pointers are much appreciated. If a £2700 bill is my only option then so be it. It just want to check first.