Thermostat randomly reboots or restarts during normal operation

Safety first: Turn off power to the HVAC system at the breaker before removing the thermostat.

Steps to attempt:

• Reseat thermostat: Remove and firmly reattach the thermostat to the wall plate to ensure solid pin contact.
• Inspect R and C wiring: Confirm that R and C wires are tightly secured at both the thermostat and furnace control board.
• Check for shared loads: If other devices (e.g., humidifier, zoning panel) share the transformer, an HVAC technician should verify the transformer is adequately sized.
• Firmware update: Use the Sensi app to check for firmware updates that may address stability issues.

When to replace: If reboots continue with stable wiring and supply voltage, the internal electronics are likely failing and the thermostat should be replaced.