Your boiler has detected an issue with how it monitors water levels, meaning it cannot confirm there is enough water to safely provide heating or hot water.

Fault recorded in Fault History

What causes this fault?

This fault occurs when the boiler's internal computer loses communication with the sensor that monitors water levels. The most common reason is that the sensor itself has failed due to age or internal corrosion, or the electrical wiring connecting it to the main control board has developed a loose connection.