Thermostat shows E10 and may indicate 'Overheat protection' or 'Thermostat temperature too high'; screen may dim or shut down.

Safety note: Overheating can damage electronics but is not usually an immediate shock hazard.

Steps:

• Check location: Ensure the Rheem smart thermostat is not directly above a supply vent, fireplace, or other heat source. If it is, relocation is recommended.
• Seal wall opening: Remove the thermostat and inspect the wall box. If hot air is leaking from the wall cavity (e.g., from an unsealed return duct), seal the opening with foam gasket or caulk, keeping wires accessible.
• Reduce sunlight: If the thermostat is in direct sun, add a shade or curtain to limit radiant heating.
• Allow cooldown: Leave the thermostat off the wall for 15–20 minutes to cool, then reinstall and monitor.
• If E10 persists in a normal environment: The internal temperature sensor or protection circuit may be faulty, requiring thermostat replacement.