Thermostat shows E08 and the measured room temperature is clearly incorrect (e.g. 0°C or 99°C).

Safety first: Turn off power before removing the thermostat from its base.

Steps to correct:

• 1. Check installation position: Ensure the thermostat is not above a radiator, in direct sunlight, behind curtains, or on an external wall subject to drafts.
• 2. Reboot and recalibrate: Power-cycle the thermostat and, if available, run any built-in sensor calibration or offset function in the settings menu.
• 3. Inspect for contamination: Remove the thermostat from its base and gently blow out dust. Do not use liquids. Check for signs of moisture damage.
• 4. Compare with external thermometer: If the reading is consistently off by a fixed amount, use the thermostat’s temperature offset feature to correct it.

When to call a professional: If the reading is wildly unstable or stuck at extreme values and E08 persists, the internal sensor or PCB is faulty and the thermostat should be replaced.