I have a 2003 325I when coming to a stop with the foot on the brakes (lightly), as the transmission downshifts I can hear a thud/clunk coming from the rear end of my car along with a increase in the RPM's. I also hear it as soon as I let off my foot of the gas pedal or accelerate causing my car to not drive properly and my transmission to hit my suspension very hard. So, I've searched this issue and other BMW forums and found that other people had the same complaints and this exact problem which is dangerous & very scary.

- Elkhart, IN, USA

My vehicle has the same incident about a dozen of times in the last 4-5 years. The vehicle suddenly had check engine light, ABS light, traction control light, and brake light on, engineer started to knocking, speed forced down to less than 30 mph within in seconds. It was quite scaring when the vehicle was on the highway with speed at ~50-70 mpg. My dealer has made several repairs, changing everything in this speed controlling system multiple times according to the book, including throttle body twice, electric harness three times, and control computer unit once, but the problem recurs. Occasionally, resetting the system and/or restarting the car, and sometimes reconnecting every parts of the system can avoid the problem for a while (from a days to 1-2 years). Although it is unpredictable in when, it would come back. The problem seems to come more often when the weather become more wet. This mimics the behavior of the poor electric connections controlling the tails and turning lights of the same model, which was recalled by BMW a couple of years ago. It seems that the same electric connectors are used in this speed controlling system. Obviously, this problem is more dangerous than the signaling light issue since it is more likely to lead to severe accidents/crashes in the highway; I might be dead or severely injured if I did not responded quickly enough when was in I-95 for example.

- Charlottesvillle, VA, USA