Dehumidifier or humidifier beeps and displays E4; unit stops operation.

Safety: Turn off and unplug the Klarstein unit before handling the water tank or internal components.

• Empty and clean tank: Remove the water tank, empty it completely, and rinse with warm water. Check for slime, scale, or debris that could block the float.
• Inspect float mechanism: On dehumidifiers, the float is usually inside the tank or in a side chamber. Move it up and down by hand; it should move freely and return by gravity. Clean any buildup with mild detergent and a soft brush.
• Check tank seating: Reinsert the tank fully. Many Klarstein units use a mechanical lever or magnet in the tank to actuate a switch inside the body. If the tank is not seated correctly, E4 will appear.
• Test the level switch: With the unit unplugged and the cover removed, locate the water level switch (reed switch or micro-switch). Manually actuate it while checking continuity with a multimeter. It should change state when the float is raised.
• Repair or replace: If the switch does not change state, replace the water level switch assembly. Ensure the magnet or lever from the tank aligns correctly with the new switch.
• Check wiring: Inspect the harness from the level switch to the main PCB for breaks or loose connectors. Reseat the plug firmly.