BoilerFaultCodesTechnical description
Flue/Fan fault (Pressure switch has disconnected or failed to connect)
What causes this fault?
This fault occurs when the boiler's safety sensors detect that the fan isn't spinning at the right speed or the exhaust gases aren't being pushed out of the flue pipe correctly. The most common reasons are a build-up of dirt inside the fan, a blockage in the external flue pipe, or a failure in the pressure switch that monitors air flow. Because the boiler cannot guarantee that harmful fumes are being safely removed, it shuts down as a critical safety precaution.
This fault is more frequent during periods of high winds, which can create back-pressure in the flue and interfere with the air pressure sensor's readings.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.