Your boiler's outdoor temperature monitor is not sending a signal, which may cause your heating to behave unpredictably based on the weather.

Outside Sensor Fault

What causes this fault?

This fault occurs when the boiler loses communication with the small sensor located on the exterior wall of your home. It is usually caused by water ingress damaging the sensor's internal circuitry or a loose connection in the wiring that links the sensor to the boiler's main control board.