Your boiler's outside temperature sensor has developed a fault or disconnected, meaning the system may struggle to automatically adjust its heating levels based on the weather.

Optional external probe error

What causes this fault?

This fault occurs when the boiler loses communication with the sensor located on the outside of your property. The most common reason is that the sensor's internal components have corroded due to weather exposure, or the thin electrical wires connecting it to the boiler have snapped or come loose.