Your boiler's internal memory has encountered an error and has reverted to its factory default settings, meaning it needs reconfiguring to work with your heating system.

Reset all parameters

What causes this fault?

This fault occurs when the boiler's internal computer suffers a data corruption or a temporary power fluctuation that wipes its stored memory. Effectively, the boiler has forgotten how to communicate with your specific heating setup and has reverted to its original factory settings for safety. The most common reason is a failing primary circuit board or a loose connection with the small 'code plug' that stores the unit's identity.