Remove windshield wiper assembly Cover dust filter. Remove windshield wiper bearing. Use special tool 140 589 00 07 00 Remove 4 screws and remove water collector. Remove phillips head screws (3) and remove cover. Remove 5 screws and remove cover (inside heater housing). Apply vacuum to the pneumatic seal of active charcoal filter. Use special tool 201 589 13 21 00. NOTE : For removal and installation of the active charcoal filter the pneumatic seal must remain evacuated. Vacuum tester remains connected. Pull out active charcoal filter towards the top. Use special tool 140 589 02 33 00. NOTE : The active charcoal filter can not be cleaned, it always must be replaced.