Your boiler started to heat up but the flame went out unexpectedly while it was running.

Loss of flame during operation

What causes this fault?

This fault occurs when the boiler successfully lights, but the internal sensors lose track of the flame while it is running, causing the system to shut down for safety. The most common reasons are a worn-out sensing probe that can no longer 'see' the fire, or an unstable gas supply that prevents the flame from staying consistent.