Your boiler's internal computer is having trouble communicating with its identity chip, meaning it doesn't recognize its own settings.

Coding plug not detected.

What causes this fault?

This fault occurs when the boiler's main control board loses its connection to a small electronic chip that tells the unit exactly how to operate. The most common reason is a loose connection or a component failure on the circuit board, often caused by natural vibrations or moisture getting into the internal components over time.