This hose connects from the oil separator to the lower oil dipstick tube. A common problem with modern BMWs is with the oil separator, or CVV system. Over time, the oil vapours the system that is designed to capture and recirculate can cause clogged lines and other blockages, resulting in oil leaks, reduced engine performance, and other issues. We offer this replacement hose from Febi Bilstein. 

OEM Part Number: 11157532649
Rein Part Number: ABV0100R