Your boiler's electronic control board has lost its configuration settings or has been set up incorrectly, preventing the system from operating.

Appears if a problem exists with the jumper tags configuration of the PCB.

What causes this fault?

This fault occurs when the boiler's central brain, the printed circuit board, cannot identify which specific model of boiler it is supposed to be controlling. It is usually caused by the physical 'jumper tags' on the board being loose, missing, or incorrectly positioned, often following a power surge or a previous repair where the board was replaced. Without these settings, the boiler shuts down as a safety precaution because it doesn't know its own capacity or operating limits.