Your boiler has detected an internal electrical communication error, which means it has stopped working as a safety precaution.

Boiler electr. system fault

What causes this fault?

This fault occurs when the boiler's internal computer is unable to communicate with its electrical components, effectively causing the system to lose its 'train of thought'. The most common reason is a hardware failure within the main circuit board or a loose connection in the wiring that links the various sensors together. Because the boiler can no longer verify that it is operating safely, it shuts down immediately to prevent damage.