I'm new to the Audi scene and would love to know what the approx. 3" black disk on my windscreen is for, it has 2 wires going to it The previous owner had the car for 5 years and he still didn't know what it was for. I just had the timing belt done and the garage were also unaware of what it is, only that it is a retro fit. Once i work out how, I'll upload some pics to hopefully resolve the issue.