Your boiler's main internal computer has developed a communication failure, meaning it can no longer control the heating and hot water functions.

Main PCB fault

What causes this fault?

This fault occurs when the boiler's main control board suffers an internal component failure or a memory error, preventing it from processing instructions. It is often caused by general electrical wear and tear over time or a sudden power surge that damages the delicate circuitry on the board. In some cases, loose or damaged wiring between the board and other internal components can also trigger this communication breakdown.