Humidifier will not run and displays E1 on the control panel

Safety first: Unplug the humidifier from the wall outlet before opening any covers. Never work on the unit while it is connected to power.

Step-by-step checks:

• Power-cycle the unit: Unplug for 5 minutes, then plug back in and try again. Temporary logic glitches can trigger E1.
• Inspect the temperature sensor lead: On many BONECO digital humidifiers (e.g., U700, U650, H300), the room temperature sensor is a small NTC probe on a two-wire harness leading to the main PCB. Remove the front or rear cover per the user manual and locate the sensor near the air intake grille.
• Check for loose or corroded connectors: Gently unplug and re-seat the sensor connector on the main control board. Look for green/white corrosion or broken pins. Clean light oxidation with isopropyl alcohol and a cotton swab, then reconnect firmly.
• Visual inspection of the sensor: Ensure the sensor capsule is intact and not broken off or covered in dust. If heavily dusty, clean with a soft brush—do not soak it.
• Basic resistance check (for advanced DIYers): With the unit unplugged, disconnect the sensor and measure resistance with a multimeter. A typical NTC sensor will show several kΩ at room temperature and change when warmed by your fingers. If it reads open (OL) or 0 Ω, the sensor is defective.
• If the sensor is defective: Replace the room temperature NTC sensor assembly with a compatible BONECO part. Route the new sensor wiring the same way as the original and secure it away from hot components.
• If the sensor tests good: The fault may be on the main PCB sensor input circuit. In this case, replacement of the main control board is usually required and is best done by an authorized BONECO service center.