Humidifier shows 'Er' or 'Err' and will not operate

Safety: Unplug the humidifier before opening the casing.

• Power cycle: Unplug for 10–15 minutes, then reconnect. Many Stadler Form humidifiers clear transient errors after a full reset.
• Check internal connectors: Remove the top or bottom cover to access the control board. Inspect and reseat connectors for the humidity sensor, temperature sensor, and water level sensor.
• Look for moisture: If condensation or water has entered the electronics compartment, dry the unit thoroughly in a warm, dry room for 24 hours before retrying.
• Replace faulty module: If a specific sensor is identified as faulty (e.g., open-circuit on multimeter), replace it with the correct Stadler Form part.
• Control board replacement: If all sensors and wiring are intact, the main PCB may be defective and require replacement.