That valve is most likely the BMW special wamadine PCV valve (not its real name of course). This valve has a history of this type of failure in extreme cold temperatures on M54 engines. They even have an upgraded 'cold weather option' upgraded valve....
Do a search, especially on the E46 chassis and you will see.
How does something immoral, when done privately, become moral when it is done collectively?
Furthermore, does legality establish morality?
Slavery was legal; apartheid was legal; Stalinist, Nazi, and Maoist purges were legal. Clearly, the fact of legality does not justify these crimes. Legality, alone, cannot be the talisman of morel people. - Walter E. Williams