I had to replace the ACC-Sensor in my 435xi. Dealer wanted $6000 to do it. I bought a used one for $270 and installed it and the radar came back on. I could again use the adaptive cruise control, however, there is an error message regarding the front camera being partially obstructed and reduced functionality. I spoke to the dealer and they told me the ACC-Sensor needed to be programmed and aligned to function properly after installation. Brought it in and they tried to program it but told me because it was used it was tied to the original vehicle and it could not be coded properly, at least they couldn't manage it. Does anyone have any experience with this and can point me in the right direction? Thanks.