Your boiler's internal computer has lost its identity because the memory chip is either loose or failing.

Software version CF

What causes this fault?

This fault occurs when the boiler's main control board loses communication with a small memory chip called a code plug, which tells the boiler exactly which model it is. The most common reason is that the chip has vibrated loose over time or its electronic circuits have failed, meaning the boiler can no longer operate safely without knowing its own identity.