Thermostat shows much higher or lower room temperature than actual

Safety: Turn off power to the HVAC at the breaker before removing the thermostat from the wall.

Steps to correct:

• Check placement: Ensure the thermostat is not above electronics, lamps, or other heat sources, and not in direct sunlight.
• Seal wall opening: Remove the thermostat and seal any large gaps in the wall behind it with foam or putty to block drafts from inside the wall.
• Compare with reference: Place a reliable thermometer near the thermostat and compare readings over 30 minutes.
• Adjust offset (if available): Some Sensi models allow a temperature offset in settings. Apply a small offset to match the reference thermometer.

When to replace: If the reading is unstable or off by a large amount even in a good location and with offset applied, the internal sensor is likely defective and the thermostat should be replaced.