BoilerFaultCodesTechnical description
Air flow proving fault - that is fan or air pressure switch.
What causes this fault?
This fault occurs when the boiler's internal safety system can no longer confirm that the fan is successfully pushing harmful exhaust gases out of the flue. The most common reason is that the fan has failed, the air pressure sensor has malfunctioning electrical contacts, or the small tubes connecting them have become blocked with dust or debris.
This fault is more common during the first cold spells of autumn, as mechanical fans that have been idle over the summer can seize up when they are suddenly required to run frequently.
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.
Find a Gas Safe engineer
Search the official register →