Thermostat shows error 111 and reports low battery on wireless sensor or remote unit.

Safety: Use only recommended battery types; do not mix old and new cells.

• Replace batteries: Open the wireless sensor or remote unit and replace all batteries with new, high-quality alkaline or lithium cells as specified by Ariston.
• Clean contacts: If you see white or green corrosion on battery contacts, gently clean with a cotton swab and isopropyl alcohol (device powered off).
• Improve signal: If low battery warnings recur quickly, move the sensor closer to the thermostat or reduce obstacles to lower RF power consumption.
• Check orientation: Ensure batteries are inserted with correct polarity (+/−) as marked.