BoilerFaultCodesTechnical description
Air Pressure Fault (fan, air pressure switch, flue, or venturi).
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the fan isn't moving enough air or that the exhaust gases aren't leaving the building correctly. The most common reason is a buildup of dirt in the small tubes known as the venturi, or a mechanical failure in the fan or air pressure switch. Because the boiler cannot guarantee that harmful fumes are being safely removed, it shuts down immediately as a safety precaution.
This fault is more common during periods of high winds, which can cause pressure fluctuations in the flue that interfere with the air pressure switch 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.