The "CLEAN" warning activates after approximately 60 brew cycles. It's a reminder to run the Auto Clean cycle.
To run the cycle: combine 6 cups white vinegar and 4 cups cold water in the carafe. Pour into the water reservoir. Place the empty carafe on the plate. Press and hold the On/Off button for 4 seconds. The cycle will run for 45-60 minutes and shut off automatically.
Afterwards, brew a full carafe of fresh water before making coffee.