Dehumidifier will not start; display shows E1 shortly after power-on.

Safety first: Unplug the Trotec dehumidifier from the mains before opening any panels. Do not work on the unit while it is connected to power.

Steps to check and fix:

• Power reset: Unplug the unit for 5–10 minutes, then plug back in and try again. Sometimes E1 is a transient sensor read error.
• Locate the room sensor: On most Trotec dehumidifiers, the ambient NTC sensor is clipped near the air intake grille or mounted on the evaporator inlet area, connected by two thin wires to the main PCB.
• Inspect wiring: Remove the front or side cover as per the user manual. Check the sensor cable for cuts, pinches, or signs of rodent damage. Ensure the plug is fully seated on the main PCB.
• Test the sensor: With a multimeter set to resistance (kΩ range), measure across the two sensor leads. At room temperature (20–25°C), most Trotec NTC sensors will read between roughly 5–20 kΩ. An open circuit (OL) or 0 Ω indicates a failed sensor.
• Clean and reconnect: If the connector is oxidized, clean it gently with contact cleaner and re-seat it firmly.
• Replace the sensor if faulty: If resistance is far out of range or intermittent when you gently move the cable, replace the ambient NTC sensor with a compatible Trotec sensor assembly.
• Check the PCB if sensor is OK: If the sensor tests good but E1 persists, the sensor input circuit on the main control board may be defective. In that case, replacement of the main PCB is usually required and is best done by a qualified technician.