The Gates emission control hose for 2009–2016 Audi A4 4‑cyl 2.0L connects the PCV valve to its tube as part of the emissions system. It serves as a replacement for the factory PCV-to-tube hose, preserving the intended routing between the crankcase/PCV area and the intake tube so the vehicle maintains the designed flow path for emissions control.

Gates 09-16 Audi A4 4-Cyl. 2.0L PCV Valve To Tube Emission Control Hose