Your boiler is displaying an error code for a feature that isn't actually used on this model, which usually indicates a simple electronic glitch or a programming error.

This feature is not required on this appliance

What causes this fault?

This fault occurs when the boiler's internal computer becomes confused and attempts to monitor a component or feature that doesn't exist on this specific model. It is usually triggered by a temporary electronic glitch or the circuit board being programmed with the wrong software settings during a repair or power surge.