Your boiler has detected a problem with the sensor that monitors water pressure, meaning it cannot accurately tell if there is enough water in the system to run safely.

Water pressure sensor signal outside correct range, the sensor signal is too high

What causes this fault?

This fault occurs when the boiler's internal computer receives an electrical signal from the water pressure sensor that is completely outside of its expected range. The most common reason is that the sensor itself has developed an internal electrical short or has become blocked with system debris, causing it to send a false high-voltage reading. In some cases, a damaged or damp wiring harness can also interfere with the signal being sent to the main control board.