DIAGNOSIS The float switch in the top-fill reservoir is stuck or obstructed. This is a common point of failure for the water level sensor.
FIX Power off and unplug. Remove the water tank. Inspect the small black float on the side of the tank's docking area. Manually move the float up and down its track several times. Check for mineral scale or debris blocking its movement. Clean with a damp cloth. Reinstall tank and restart.
IF THAT DIDN'T WORK The float switch itself may have failed. You will see error code E-01 or E-02 flash if the main board detects a sensor fault. Unplug for 5 minutes to reset. If error returns, the float switch assembly requires replacement.
HEADS UP Always use the machine on a level surface. A tilt of more than 2 degrees can cause the float to read inaccurately, triggering false 'add water' alerts.