Your boiler is struggling to read its own water level because of an electrical sensor issue, which has caused it to stop working as a safety precaution.

Water pressure sensor fault

What causes this fault?

This fault occurs when the boiler's internal computer loses communication with the sensor that monitors water pressure. The most common reason is that the sensor has developed an electrical internal short or the wiring connecting it to the main control board has become loose or damaged. Without an accurate pressure reading, the boiler shuts down to prevent itself from firing while potentially dry.