Your boiler has lost communication with the sensor that measures the temperature outdoors, which may cause your heating to run less efficiently.

Outside Sensor Fault

What causes this fault?

This fault occurs when the boiler's main control board loses the electronic signal from the sensor located on the outside of your home. The most common reasons are physical damage to the external sensor unit or the wiring connecting it to the boiler becoming loose, corroded, or damaged by the elements.