Thermostat displays E17 and indicates an internal sensor calibration error; temperature readings may be offset.

Safety: No high‑voltage work is required.

• Compare with reference: Place a reliable digital thermometer near the thermostat and compare readings after 30 minutes.
• Apply offset (if available): In the thermostat settings, use the temperature calibration/offset feature to correct minor differences (e.g., ±1–2 °C).
• Factory reset: Perform a factory reset to reload default calibration data, then recheck readings.
• Relocate if exposed: If the thermostat is in a draft, direct sun, or near a heat source, relocate it to a more representative location.
• Replace if large error remains: If readings are off by more than the offset range and E17 persists, the internal sensor or calibration is defective; replace the thermostat.