E11 displayed and thermostat cannot detect humidity level or shows 0%/100% constantly.

Safety first: Turn off power to the thermostat before removing the front cover.

• Step 1 – Reboot and reset: Power cycle the thermostat and, if needed, perform a factory reset to rule out software glitches.
• Step 2 – Inspect sensor area: Remove the front cover and locate the humidity sensor (often a small IC or module near air vents). Look for paint overspray, dust buildup, or signs of moisture.
• Step 3 – Gentle cleaning: If dusty, blow with dry compressed air. Do not use water or aggressive solvents on the sensor. Avoid touching the sensor surface with fingers.
• Step 4 – Check installation environment: Avoid installing the thermostat in bathrooms or areas with persistent high humidity and condensation, which can permanently damage the sensor.
• Step 5 – Replace front module: If E11 persists and humidity readings are clearly wrong, the humidity sensor is likely defective. Replace the thermostat front/user interface module or the entire thermostat.