Your boiler's main control computer is experiencing a serious internal error and has stopped the system to prevent further issues.

Internal fault (PCB)

What causes this fault?

This fault occurs when the boiler's main control board suffers an internal electronic failure or a loss of communication with its connected sensors. It is usually caused by aging electrical components on the circuit board wearing out or, in some cases, a loose connection in the internal wiring harness. Because the 'brain' of the boiler can no longer process safety data, it shuts down the system entirely to prevent accidents.