Thermostat displays E2 and shows a problem with the outdoor temperature or remote sensor

Safety: No high-voltage work is required for this fault. You can troubleshoot with power on.

• Step 1 – Replace SmartSensor batteries: Open the SmartSensor housing and replace the coin-cell battery (typically CR2477 or model-specific). Ensure correct polarity.
• Step 2 – Reposition the sensor: Move the SmartSensor closer to the thermostat and away from metal doors, refrigerators, or electrical panels. Avoid placing it directly above HVAC vents.
• Step 3 – Re-pair the sensor: On the ecobee, go to Menu > Settings > Sensors, remove the problematic sensor, then add it again following on-screen instructions.
• Step 4 – Reduce interference: Move Wi‑Fi routers or cordless phone bases at least a few feet away from the thermostat and sensor if possible.
• Step 5 – Test with another sensor: If another SmartSensor works fine, the original sensor is likely defective and should be replaced.