Error 106 on thermostat; room temperature reading is clearly wrong (e.g. shows 5°C or 40°C indoors).

Safety: Turn off power to the thermostat circuit before removing it from the wall.

• Check location: Ensure the thermostat is not installed above a radiator, in direct sunlight, near an oven, or in a drafty hallway. If it is, consider relocating it to an interior wall about 1.5 m above floor level.
• Inspect casing: Remove the front cover and check for signs of condensation, corrosion, or insect ingress. Allow to dry if damp (power off) and clean gently with dry air.
• Compare with reference thermometer: Place a reliable thermometer next to the thermostat for 15–20 minutes and compare readings. If the thermostat is off by more than 2–3°C, use the calibration/offset setting in the installer menu to correct minor deviations.
• Persistent large error: If readings remain wildly inaccurate, the internal NTC sensor or PCB is defective. Replace the thermostat unit.