I was informed by my dealer that it was a counter threshold. the design life of the SBC pump valves was set at an expectation of 250,000 brake activations. some early delivery German tax drivers had exceeded this level after two years. On inspecton of the pumps/valves after this volume of usage Mercedes found there to be no deteriation in performance of the SBC system. my understanding of the rdecall is that they disable the counter as failure on a normal car is likely to be 10 years + away, and will probably deteriorate slowly much like a normal servo. I am also led to believe that without SBC the system is still well above the required legal braking reqirements, and far exceeds a normal car when the servo fails. All in all, i'm not worried about brake failure on my car.