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 computer sends power to the fan but does not receive a signal back confirming that air is moving through the flue. The most common reasons are a motor failure within the fan itself or a blockage in the small plastic tubes that sense air pressure. Without this confirmed airflow, the boiler cannot safely light the flame and will stay in a safe mode.
This issue can occasionally follow a period of heavy wind or storms, as strong gusts can sometimes interfere with the pressure sensors or blow debris into the external flue pipe.
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.