Your boiler's internal computer parts are failing to talk to each other, meaning the system cannot receive the instructions it needs to start up.

No Connection To Primary Pcb

What causes this fault?

This fault occurs when the boiler's internal control boards lose the ability to speak to one another, often due to a loose connection or a component failure. The most common reason is that the main control board has developed an electrical fault or the wiring linking the display screen to the central computer has degraded.