Q1: Why won't the descale light turn off after cleaning the machine?
Modern Keurings use firmware routines that track the volume of fluid run while in designated descaling mode rather than using an optical scale sensor. If you ran cleaning cycles without initiating the machine's official descaling sequence, the light remains on. Enter descaling mode by powering down and holding the appropriate cup buttons, complete a full tank purge with fluid, followed by a full freshwater tank rinse to let the sensor acknowledge the completed maintenance cycle.
Q2: Can I use boiling water or baking soda to clean internal clogs?
Never run boiling water or baking soda through your machine. Pouring pre-boiled water into the reservoir disrupts internal pump thermistors and can warp silicone seals. Baking soda is an alkaline base ($NaHCO_3$), whereas limescale requires an acid to dissolve. Running baking soda through your brewer creates insoluble chalk deposits that worsen internal pipe blockages.
Q3: How often should needle unclogging and descaling be performed?
Perform a chemical descaling cycle every three months if using filtered or soft water, and every six to eight weeks if brewing with municipal hard water. Clear needles with a paperclip once a month, or immediately whenever you experience sputtering or incomplete cup volumes.
