Checking for leaks
WARNING: This page is about a different car, the 2010 BMW M6, 2009 BMW M6, and 2008 BMW M6. However, it is still accessible from the selected car via links, so may be relevant.
The following illustration shows the arrangement of the power steering components and lines.
Courtesy of BMW OF NORTH AMERICA, INC.
Check all visible connections, hoses, lines and steering gear for traces of fluid.