Thats right the bolts behind the strips wont come out and can be left alone.Thanks very much - just finished the job.
For future reference, you do not need to remove the rear diffuser/valance - It is part of the bumper and comes off with it attached.
You also do not need to undo the bolts behind the bumper strips.
Took me an hour and a half.
Just my luck it is one of the middle ones I need to change as it's making no sound when you do the sound test on it..!!!You only need to take the bumper off for the middle 2 sensors, the outer 2 are cliped into the trim strips and are easy to change.
Hi Richard,I think you can just get them off by taking the diffuser off, but that's almost more work than taking the bumper off.
The correct part number for Carbon Black is 66 20 7 964 087 or 66 21 7 890 441 depending on the build date. However many people use a cheaper sensor and paint it yourself, even though BMW say specifically not to do this.