The thermostat shows a much higher or lower room temperature than actual.

Safety first: No special hazards.

• Compare with a thermometer: Place a reliable thermometer near the thermostat and compare readings after 15–20 minutes.
• Adjust offset: Use the thermostat's calibration/offset setting to correct small differences (e.g., ±1–2°C).
• Relocate thermostat: If the thermostat is on an external wall, above a radiator, or near a heat source, move it to an internal wall in a representative room.
• If a large error remains: The internal sensor may be faulty. Replace the thermostat or add a Vokera remote room sensor if supported.