The thermostat shows a temperature that is clearly inaccurate compared to other thermometers in the home.

Safety: No high-voltage work is required.

• Check location: Ensure the thermostat is not in direct sunlight, above electronics, or directly in the path of a supply register. These can cause false readings.
• Seal wall opening: Remove the thermostat and use foam or putty to seal the hole in the wall behind it to prevent drafts from the wall cavity affecting the sensor.
• Compare with reference: Place a reliable digital thermometer near the thermostat and compare readings after 15–20 minutes.
• Adjust offset: In the thermostat settings, adjust the temperature calibration/offset to match the reference thermometer if the difference is small.
• Replacement: If the thermostat reading is erratic or far off, even after offset adjustment and proper placement, the internal sensor may be defective. Replace the thermostat.