Checking blow-off valves

WARNING: This page is about a different car, the 2010 BMW X6, 2009 BMW X6, and 2008 BMW X6. However, it is still accessible from the selected car via links, so may be relevant.

Necessary preliminary tasks:

Remove both blow-off valves

NOTE: To check the function of the blow-off valves (2), it is necessary to build up vacuum pressure at the valves.

Establish vacuum pressure with the BMW auxiliary diagnosis unit - vacuum.

Connect vacuum hose (3).

Establish vacuum pressure at 500 mbar.

Plunger (1) must visibly release the opening in the direction of the arrow as far as it will go.

Fig 1: Identifying Plunger, Blow-Off Valves And Vacuum Hose

Courtesy of BMW OF NORTH AMERICA, INC.

IMPORTANT: Plunger (1) must maintain this position while vacuum pressure is being created.
If this is not the case, replace the blow-off valve (2).