Your filter has been doing such fine job but all good things come to an end. The warning light is there. Get yourself a replacement filter. Keep your air purified as it should be. Three layers. High-density mesh cloth for large particles. HEPA filter to catch all the small particles. The photocatalyst filter to clear out all those microelements in the air. Open the lid. Pull out your old filter and dispose of it in the bin. Slot your new filter in. Close the lid. Bingo. You are now ready to filter your air again. Buying a filter is an investment in your health. If you live near a main road or construction site, you will know exactly what I am talking about. Your filter will catch all that dust.