Your boiler has lost its flame while running and is unable to automatically restart, likely because the gas flow is being interrupted.

Operating failure: Ignit. unsuccessful - Gas supply interrupted intermittently. Re-ignition failed.

What causes this fault?

This fault occurs when your boiler successfully starts but lose its flame while it is trying to heat your home or water. The most common reasons are a temporary drop in gas pressure, a build-up of debris on the burner, or a faulty internal component that can no longer detect the flame. If it happens during very cold weather, it may also be caused by a frozen external pipe blocking the system's drainage.