Engine Crankcase Breather Hose – Oil Reservoir to Air Filter Housing Gas Spring Robust Build: Constructed to endure

Robust Build: Constructed to endure harsh driving conditions and long-term use

0 TFSI Audi A4 B7 2004–2008 2

Part Number 3809401

Threaded mount and male connector for direct fit

0V6 Audi Q7 2017–2022 3

Engine Crankcase Breather Hose – Oil Reservoir to Air Filter Housing Gas Spring Robust Build: Constructed to endureEngine Crankcase Breather hoses are part of a vehicles Positive Crankcase Ventilation (PCV) system. The job of the PCV system is to allow pressure to escape from the crankcase in a controlled manner. It is necessary to vent the crankcase of positive pressure caused by engine blow by (gas from the combustion event that leaks past the pistons.) This blow by gas is routed back into the intake air stream thereby reducing the emission of unburned