Thermostat temperature reading is consistently higher or lower than actual room temperature

Safety first: Turn off power before removing the thermostat from the wall if you will access wiring or the wall cavity.

• Step 1 – Compare with reference: Place a reliable thermometer near the thermostat and compare readings over 15–20 minutes.
• Step 2 – Adjust calibration: In the thermostat settings, apply a small temperature offset to match the reference thermometer.
• Step 3 – Seal wall opening: Remove the thermostat and seal large gaps in the wall opening with foam or putty to prevent drafts from affecting the sensor.
• Step 4 – Check location: Ensure the thermostat is not in direct sunlight, near exterior doors, or above supply registers. If it is, consider relocating it to a more representative location.
• Step 5 – Replace sensor/thermostat: If the reading remains inaccurate even in a good location and with calibration, the internal sensor may be failing and the thermostat or sensor module should be replaced.