BoilerFaultCodesWhat the manual says
Manufacturer manualAir flow proving fault - that is fan or air pressure switch
What causes this fault?
This fault occurs when the boiler's internal computer tries to start the fan but cannot confirm that a safe flow of air is moving through the system. The most common cause is either a mechanical failure of the fan itself or a blockage in the small plastic tubes that connect to the air pressure sensor, preventing the boiler from knowing it is safe to ignite.
This issue can be more common during periods of high winds, as strong gusts can sometimes interfere with the pressure sensor's ability to get a stable reading through the external flue.
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.
Avoid the next call-out bill
A cover plan would handle faults like Neon3: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.