Thermostat shows temperature that is clearly inaccurate compared to the actual room temperature.

Safety first: No high-voltage work is required.

• Step 1 – Compare with reference: Place a reliable digital thermometer next to the thermostat and compare readings after 15–20 minutes.
• Step 2 – Check location: Ensure the thermostat is not in direct sunlight, near a supply register, or above electronics. If it is, consider relocating it to an interior wall in a representative area.
• Step 3 – Seal wall opening: Remove the thermostat and use foam or putty to seal the hole in the wall behind it to prevent drafts from affecting the sensor.
• Step 4 – Adjust calibration: If the thermostat offers an offset or calibration setting, adjust it to match the reference thermometer.
• Step 5 – Replace thermostat: If readings remain erratic or far off, the internal sensor may be failing and the thermostat should be replaced.