Thermostat shows E2 and will not complete setup or control HVAC

Safety: Switch off power to the furnace/air handler at the breaker before removing the thermostat from the wall.

• Check environment: Confirm the thermostat is not installed in a bathroom, above a humidifier outlet, or in an area with condensation. Excess moisture can damage the internal humidity sensor.
• Dry out the unit: If the thermostat was exposed to moisture, remove it from the wall plate and let it sit in a dry indoor area for 24 hours. Do not use heat guns or hair dryers.
• Inspect housing and contacts: Look for signs of corrosion on the wall plate contacts and the back of the thermostat. Clean gently with a dry, lint-free cloth.
• Power cycle and reset: Restore power, then perform a factory reset via the thermostat or Alexa app and re-run setup.

If E2 persists: The internal humidity/environmental sensor circuit on the main board is likely damaged. Replace the thermostat assembly.