Clean the filter and vent hose
The fluff filter is situated in the door access - open the door and it is in the bottom of the door opening, lift it out and clean any fluff build up. If you have already done this but the filter warning light is still coming on then it could be due to a build up of fluff in the vent pipe or outside venting cover. Should the vent pipe be kinked or trapped this will also bring the filter light on. Pull the machine out and detach the white corrugated vent pipe. Clean it out and re fit making sure it does not get crushed when the machine is pushed back. Finally check outside the property where the air comes out ensuring the outside vent cover is lint free and not obstructed.
The vent tube is at the rear of the machine