OH boy, for the last two years of the lease of my 650i, I have been continually plagued by malfunction the sensor which detects a top open condition. There apparently are sensors inside the convertible top which sound an alarm warning to the driver if they exceed 5 mph while operating the top, or alert the driver to a "top not locked" condition if that occurs. There is a warning on the master nav/control screen and an audible sound. Finally the indicator light down at the top actuator buttons flashed red and renders the raising or lowering of the top inoperative.
Several problems go beyond just this warning
1. All the devices get locked out - windows freeze in the down position, trunk wont open, top freezes and will not move. All this occurs for as long as you drive the car, AND will stay in place for 45 minutes after shutting the car off. So if it is raining, you are gonna get wet.
2. This happens over and over and over and over and over and over, maybe 12 times a week once it starts happening. So there is no operation of the top once this starts....you cannot even touch the button, becuase you will send the car into this condition - with the windows locked half way down and all aperture electronics frozen.
3. I have had this fixed at least 8 times, 2 days in the dealership many of those times to make this happen. I am managing partner of my business and just cannot afford to lose this time away from my business for something so petty.
The sensor goes out whenever there is a temperature/season change and in any case about 2 months after each fix is effected - regardless of temperature.