Your boiler’s internal computer has encountered a critical electronic failure and cannot safely operate the system.

Control box errors - possible faulty control box.

What causes this fault?

This fault occurs when the boiler's central control board suffers a hardware malfunction or loses its ability to communicate with the internal sensors. The most common reason is a component failure on the printed circuit board (PCB) or a loose connection within the main wiring harness. Because the brain of the boiler can no longer verify that it is operating safely, it automatically shuts down as a precaution.