BoilerFaultCodesYour boiler has stopped working because it cannot confirm that the internal fan is safely clearing waste gases from the system.
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 happens when the boiler's safety system cannot detect a steady flow of air through the unit. It is usually caused by a fan that has seized over time or an air pressure switch that has failed to send the signal that waste gases are being safely removed. In some cases, bits of debris or moisture can block the small plastic tubes that monitor air flow, preventing the boiler from firing up.
This issue often surfaces during the first cold spell of autumn when a boiler that has been idle all summer is suddenly forced to work at high speeds.
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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