Your boiler has lost its connection to an external safety device or a plug-in controller, causing it to stop running as a safety precaution.

Jumper 8-9 not detected.

What causes this fault?

This fault occurs when the electrical bridge that completes the safety circuit between the boiler and its external controls is broken. It is usually caused by a loose connection in the wiring, a faulty plug-in wireless receiver, or the small link plug falling out of place. Because the boiler can no longer verify that it is safe to operate, it shuts down immediately to prevent uncontrolled heating.