Crankcase Vent Hose, Genuine BMW - E46 M3 01-04, MZ3 - 11157831311

This plastic vent hose carries oil vapor from the cylinder head/valve cover to the intake manifold where it is then mixed with the intake air and burned in the engine. This is how the S54 crankcase vent system is supposed to work. But over tens of thousands of miles, the oil separator in the valve cover and this vent tube on top of the engine get clogged with oil and carbon and this reduces its effectiveness. A clogged or malfunctioning crankcase vent on the S54 will lead to excessive oil consumption (too much oil is getting burned), fault codes for fuel trim, misfires, and rough running.

The oil separator and vent tube may be cleaned but a complete replacement is the only sure way of getting the S54 oil vent system back to normal operation.

Fitment note: for 2001-2004 E46 M3 and 2001-2002 Z3 M Roadster/Coupe.