Instead of “uncoding” the mirrors (since ice formation is not usually a common every day event…but more of a sporadic occurrence)…one can use another method to lock the vehicle. One can lock the vehicle from the trunk or cargo area (using #2 or #3 in the diagram below) and the mirrors won’t fold:
I carry a briefcase M-F (sometimes Sat & Sun) which I put in the trunk or cargo area (depending on if I’m driving the f06 or f15). I discovered the trunk & cargo area central lock button DOES NOT fold the mirrors. I pop the trunk or tailgate when exiting and use comfort access to lock the vehicle which folds the mirrors. Then I retrieve my case and close the trunk/tailgate. So if you know the weather conditions are calling for freezing rain or wet conditions where the ambient temps are going to dip below freezing…you can lock the vehicle from the trunk to keep the mirrors unfolded.
Just a suggestion in case one really likes to have the mirrors folded when parked but would need an alternative (like for ice conditions) to not have them fold but the car can still be locked.