Your boiler's main internal computer has developed a serious fault and is no longer able to manage the heating process safely.

Control box failure

What causes this fault?

This fault occurs when the boiler's central control board suffers a hardware failure and can no longer process data or send signals to other components. The most common reasons for this are electrical surges, moisture ingress, or simply the natural degradation of the solder joints and capacitors over time as the unit ages.