Your boiler's internal computer has identified a mismatch or issue with its software version, which prevents it from operating correctly.

Software version of the equipment electronics (main version)

What causes this fault?

This fault occurs when there is a communication failure or a data mismatch between the boiler's main control board and its memory chip, known as the code plug. It usually happens if the electronics have suffered a software corruption or if the internal components are no longer compatible with one another. Essentially, the boiler’s 'brain' no longer recognises its own operating instructions and shuts down for safety.