Thermostat shows S002 and reports an internal sensor calibration error; temperature or humidity readings are clearly off by a large margin.

Safety: No high‑voltage work is required.

• Step 1 – Compare with reference: Place a reliable thermometer/hygrometer near GLAS and note the difference in readings.
• Step 2 – Reboot: Power cycle GLAS by removing it from the wall plate for 60 seconds, then reattach.
• Step 3 – Firmware update: Install any available firmware updates that may include sensor calibration fixes.
• Step 4 – Environmental stabilization: Ensure GLAS is not in direct sunlight, near vents, or on an exterior wall that can skew readings. Relocate if necessary.
• Step 5 – Factory reset: Back up your schedule and perform a factory reset to reload default calibration data.
• Step 6 – Replace thermostat: If S002 persists and readings remain inaccurate, the internal sensor board has likely drifted beyond correction. Replace the GLAS thermostat.