Your boiler has detected a general internal error, often linked to a small electronic glitch or a sensor that is failing to communicate correctly with the main controls.

Miscellaneous

What causes this fault?

This fault occurs when the boiler's internal computer receives conflicting information or loses contact with the main components that manage the heating process. It is typically caused by a communication breakdown between the electronic control board and the sensors, or small electrical fluctuations that disrupt the system's logic. In many cases, it indicates that the 'brain' of the boiler is no longer able to safely coordinate the startup sequence.