Your boiler's main control computer is experiencing an internal error and cannot operate safely.

Internal fault (PCB)

What causes this fault?

This fault occurs when the boiler's main control board suffers a hardware failure and can no longer process data or send signals to other components. It is often caused by an electrical surge or the natural degradation of the solder joints and capacitors on the circuit board over time. Because the board acts as the brain of the system, the boiler stops immediately to prevent unpredictable or unsafe operation.