Checking Fluid Level In Hydraulic Unit:

Necessary preliminary tasks: 

• Remove right luggage compartment wheel arch trim, refer to 51 47 161 REMOVING AND INSTALLING / REPLACING RIGHT LUGGAGE COMPARTMENT WHEEL ARCH TRIM 

Test requirements:

Open rear lid (motor-driven) twice and close again, this bleeds the system.

Rising air bubbles must not be visible.

Check fluid level in installed state.

Check distance (B) from middle of marking (3) to upper edge of pump carrier (1).

Fig 1: Checking Distance

Courtesy of BMW OF NORTH AMERICA, INC.

B = 28+/-1 mm

When rear lid is fully opened (cylinder retracted), fluid level (2) must be in area (A) of marking (3).