Your boiler has detected a temporary service issue that is preventing it from completing its ignition sequence, though it may resolve itself or require a simple reset.

Temporary fault code (Refer to section 7.10)

What causes this fault?

This fault occurs when the boiler's internal computer detects a temporary electronic glitch or a weak signal during the ignition process. It is often caused by the flame sensing electrode failing to confirm that the gas has lit correctly, or a brief dip in the communication between internal control components.