BoilerFaultCodesYour boiler has detected an issue with the way it is venting or drawing air, which has safely stopped the unit from firing up.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Air pressure switch fault
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the fan isn't moving enough air to safely carry away exhaust fumes. The most common reason is a blockage in the flue pipe or a buildup of debris in the small tubes that measure air pressure, which prevents the boiler from firing for your safety.
This issue often crops up during periods of high winds, which can create back-pressure in the flue and interfere with the air pressure switch readings.
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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A boiler cover plan would cover faults like Flashing yellow — no call-out fees, no surprises.
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