Your boiler's internal computer has suffered a technical failure and cannot communicate with the rest of the system.

Internal failure control panel.

What causes this fault?

This fault occurs when the boiler's central brain suffers a critical hardware failure or a communication breakdown between the internal components. It is often caused by an electrical surge, moisture ingress, or simply the natural degradation of the solder joints on the circuit board over time. Because the computer can no longer send instructions to the burner or pump, the boiler shuts down as a safety precaution.