I replaced one at 131015km after a a P2263. The farting stopped and the code didn't return.
The other car I replaced at 154900km, just was buzzing, no codes. New one not buzzing.
One theory is they deteriorate with age, and the filters are not fine enough to protect.
Maybe the rubber valve components. Pierburg say it's OK if they fart:
https://az25411.vo.msecnd.net/pdf/5/...5_en_51393.pdf
http://www.pierburg-service.de/ximag...076_en_web.pdf
http://www.pierburg-service.de/ximag...087_en_web.pdf