Thermostat shows E06 and cannot control humidity; humidification/dehumidification functions are disabled.

Safety: Turn off power to the thermostat before removing it from the wall.

Steps:

• Remove the thermostat and locate the humidity sensor module (often a small rectangular component with vent holes, sometimes on a daughterboard).
• Inspect for visible contamination such as dust, paint overspray, or condensation damage. Do not use liquid cleaners; gently blow away dust with dry compressed air.
• Power-cycle the thermostat by turning off the breaker for 2 minutes, then restoring power. Check if E06 clears.
• If the error persists and the sensor module is visibly damaged or corroded, the humidity sensor is usually integrated and not separately replaceable; the thermostat head unit must be replaced.
• Verify that humidity control is enabled in the installer settings; if disabled, some models may show a sensor error until configured correctly.