Thermostat displays E15 and indicates an internal temperature calibration error

Safety: No high-voltage work is required.

• Compare temperatures: Place an accurate digital thermometer near the thermostat and compare readings. Note the difference.
• Adjust offset: In the thermostat settings, look for a temperature calibration or offset option. Adjust it to match the reference thermometer if the difference is small (1–3°F).
• Factory reset: If E15 persists or the offset required is large, perform a factory reset to clear corrupted calibration data.
• Re-test: After reset, recheck the temperature reading. If it is still significantly off or E15 remains, the internal sensor has drifted beyond usable range.
• Replacement: Replace the thermostat if calibration cannot bring readings into a reasonable range.