The BMW 5-series (525i, 528i, etc.) comes from the factory with two cabin air filters for maximum interior air filtration. Most other vehicles only have one. Whether your BMW 5-series is the E39 (1995 to 2003) or the E60 model (2003 to 2010), you shouldn't have any trouble replacing the cabin air filter. The cabin air filter (also called an A/C filter or a micro filter) filters the air coming into your cabin through your air vents. Replace it annually for best results.
Shut the engine off and open the hood.
Locate the cabin air filter compartment in the rear (near the windshield) part of the passenger side engine bay.
Remove the 13mm bolt from the assembly with a socket wrench. Unplug the pressure sensor connection from the assembly.
Flip up the two latches that attach the top part of the assembly. Lift the cover and the cabin air filter from the vehicle (the filter is attached to the cover).
Remove the old filter from the compartment cover. Insert the new filter, lining up the filter and cover notches.
Inspect the bottom part of the compartment for debris (leaves, twigs, etc.) Remove them from the compartment and wipe it with a dry towel.
Insert the top part of the compartment with the new filter. Snap up the two latches, reconnect the pressure sensor and tighten the 13mm bolt.
Repeat the process for the driver side cabin air filter.
