Your boiler has lost connection with the sensor that measures the temperature outside, which helps it run more efficiently.

Outside sensor fault

What causes this fault?

This fault occurs when the boiler can no longer communicate with the small sensor installed on the exterior wall of your home. It is physically caused by either a failure of the sensor’s internal components or, more commonly, damage to the thin electrical wiring that connects the sensor to the boiler. Without this signal, the boiler cannot adjust its heat output based on the weather outside.