Your boiler has failed to light or stay lit, which is often caused by a blocked condensate pipe or a sensor detecting a problem with the ignition process.

Ignition failure/not flame sensed, condense sensor activated

What causes this fault?

This fault occurs when the boiler tries to ignite but fails to establish a steady flame, or if the safety sensors detect that the waste water cannot drain away properly. The most common reason is a blockage in the condensate trap or external pipework, which causes water to back up into the heat exchanger and extinguish the burner. It can also be triggered by worn ignition components that can no longer create a strong enough spark to light the gas.