[champignon]

There was a lot of delay in my getting this problem resolved, mostly due to a long European trip, plus the dealer being located at a distance away from my home. I finally was able to go in a couple of days ago, with the 4 new sensors that Tire Rack sent me. The dealer replaced the sensors, which apparently requires that the tires be removed from the wheels, and all 4 of the replacement sensors worked. The dealer billed me $131 for 1 hours time, which I felt was totally fair, plus they gave me a loaner car to drive for the day, which was very helpful.

I called the Tire Rack and they have now picked up the defective sensors, and agreed to reimburse me for my expense with the BMW dealer, also more than fair.

I took some photos of the replacement sensors before installation, however I cannot locate them on my cellphone. I also took pictures of the original, just removed, sensors, which clearly have "BMW" printed all over them. My assumption is that either all 4 sensors originally installed were defective (seems a bit hard to fathom), or possibly, the sensors originally installed were for an earlier version of the BMW TPMS, and erroneously installed by Tire Rack into the snow tires bound to be installed on the M2.

In any event, although I wasted a lot of time on this problem, my cost will be covered, and the nuisance appears to be over.