How to Fix / Troubleshooting

Safety: Unplug the dehumidifier. Allow any ice on the coil to melt before working inside.

Steps:

Check for icing: Remove the front cover and inspect the evaporator coil. If heavily iced, let it thaw completely and then restart. Poor airflow or low room temperature can trigger E4.
Verify room conditions: Ensure the room is above 5–10°C (41–50°F) and that air inlets/outlets are not blocked.
Locate defrost sensor: This is often the same as or similar to the pipe sensor, clipped to the evaporator tubing. Confirm it is firmly attached and not dangling.
Inspect wiring: Check the sensor wires for damage and ensure the connector is secure on the main PCB.
Test sensor: Use a multimeter to measure resistance at room temperature and compare with spec. If open or shorted, replace the defrost/pipe sensor.
Control board: If sensor and wiring are good but E4 persists, the main control PCB defrost circuit may be defective and require replacement.

Dehumidifier displays E4 and stops operating; fan may run briefly then shut off.

Possible Causes