I have just located this site and wish to congratulate the author on a very clearly explained article with excellent images. We have just had an unusually (for our normally wet maritime climate) cold spell here in Scotland with overnight temperatures down to minus 12 degrees centigrade in the cities and minus 22 in the highlands. This has caused many E92s to pop their headlamp wash units and my local dealer has advised me that they are now on world-wide back order.
A number of dealers have tried to raise the replacements as warranty issues but so far BMW UK have insisted that the responsibility rests with the owners to ensure that their bumpers (fenders in the US?) are frost free. The only way to prevent the problem seems to be to use a really strong wash solution in the winter. It appears that the washing fluid freezes up in the nozzzles in the cold temperatures and all it takes is the hydraulic pressure from the pump to force the nozzle and its cover to fly off whenever the windscreen washwipe is activated with headlamps on. Mine is lying somewhere on the M8 between Edinburgh and Glasgow.
For me the best news is that the headlamp wash unit can be deactivated by removing a fuse. I now intend to do this every winter. Thank you and best wishes to the author! My advice to anyone considering this upgrade though would be not to bother. These gizmos are much more trouble than they are worth.