Avoid unpleasant odours in recirculation modeRecirculation rangehoods draw the cooking vapours in and filter out grease and odour particles. As the cleaned air is directed back into the room, a charcoal filter is required to prevent unpleasant odours in the kitchen. Charcoal filters must be replaced on a regular basis. The control lamp on the odour filter button reminds you to replace the filter. This function is NOT active ex works. However, it is easy to activate yourself. (Please refer to your Miele rangehood operating instructions).