Your boiler's main control computer is experiencing an internal error and cannot communicate properly, which means it has shut down to protect the system.

Internal fault (PCB)

What causes this fault?

This fault occurs when the boiler's main control board suffers a critical electronic failure, preventing it from safely managing the heating process. The most common reasons include a power surge that has damaged the delicate circuitry or components reaching the end of their operational life due to heat stress over several years.