BoilerFaultCodesYour boiler has detected an issue with how it clears exhaust fumes, preventing it from firing up for safety.
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 “open”
What causes this fault?
This fault occurs when the boiler's safety sensor fails to detect that the fan is successfully pushing exhaust fumes out of the flue. The most common reasons are a blockage in the flue pipe, a build-up of dirt in the small internal tubes, or a mechanical failure within the air pressure switch itself.
This issue is more frequent during periods of heavy wind, as strong gusts can sometimes interfere with the air pressure balance needed for the boiler to start.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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