Your boiler has shut down because it has detected a problem with how the exhaust fumes are being cleared from the property.

Flue extraction duct safety device intervention

What causes this fault?

This fault occurs when the boiler's safety sensors detect that exhaust fumes are not being safely cleared through the flue pipe to the outside. The most common reasons are a blockage in the chimney or a mechanical failure in the fan that pushes the gases away. Because these fumes can be dangerous, the boiler shuts down immediately as a protective measure.