I had this issue occur again on my '08 E90 M3. I had replaced the front brakes (with new sensors) a little while ago. However, since the rears were trailing by about 2K miles, I held off on those. When I tried to reset the fronts, I got the red car on a lift, dashes on both front and rear intervals. I even tried temporarily connecting a shorted sensor to the rear and rest but to no avail. (I think, at this point, I might have been trying to reset again too soon after the last time.)
Fast forward to just a couple of days ago… I finally got around to replacing the rear brakes (and sensor). With everything in place, I reset the rears and everything fell into place. The fronts showed 41K miles remaining, the rears 45K. All is well
