Your boiler's main internal computer has encountered a processing error and cannot communicate correctly with the system.

System fault boiler electronics / basic controller

What causes this fault?

This fault occurs when the boiler's internal computer chips stop talking to each other correctly, leading to a total communication breakdown. The most common reason is a physical failure of the circuitry on the main control board or a loose internal data connection that prevents the boiler from safely managing the gas and heat. It is essentially the boiler equivalent of a 'blue screen of death' on a computer.