BoilerFaultCodesYour boiler is unable to safely clear exhaust fumes, which prevents it from firing up to provide heat or hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical 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 checks determine that the fan isn't moving enough air to safely vent exhaust fumes outside. The most common reason is a mechanical failure of the fan motor or a blockage in the small plastic tubes that signal the air pressure to the control board.
This issue can be more common during the first cold snap of autumn, as fan bearings can seize up after sitting idle throughout the summer months.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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