Dehumidifier stops running and displays E1 on the control panel; buttons may not respond or unit may not start.

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

Steps to check and correct E1:

• Power reset: Unplug the unit for 5 minutes, then plug back in and try to start it. If E1 returns immediately, continue below.
• Access the sensor: Remove the front grille and air filter. On most Keystone dehumidifiers, the room temperature sensor is a small probe clipped to the evaporator coil or mounted near the air intake, with two thin wires leading to the main PCB.
• Inspect wiring: Look for broken, pinched, or chewed wires between the sensor and the control board. Reseat the connector on the main PCB by unplugging and firmly reconnecting it.
• Check sensor resistance (advanced): With the unit unplugged, disconnect the sensor from the board and measure resistance with a multimeter. Compare to the service chart if available (typical NTC thermistor is around 10kΩ at 77°F/25°C). A reading of 0Ω (short) or infinite (open) indicates a bad sensor.
• Replace the sensor if faulty: Order a compatible Keystone room temperature sensor / thermistor for your exact model. Clip the new sensor in the same location and route the wires as originally installed, then reconnect to the PCB.
• If E1 persists: The sensor input circuit on the main control board may be defective. Replacement of the control board is recommended and is best done by a qualified technician.