WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.
Press in lock (1) before installing fast-release coupling.
Push on hose.
Fast-release coupling must audibly snap into place.