Your boiler's internal computer brain has developed a critical fault and is unable to manage the system safely.

Control box failure

What causes this fault?

This fault occurs when the boiler's main electronic circuit board suffers a hardware failure or a memory error, preventing it from processing safety data. It is often caused by long-term heat exposure degrading the electrical components or a sudden power surge that damages the sensitive microprocessors. Effectively, the boiler can no longer trust its own internal instructions and shuts down to prevent an accident.