BoilerFaultCodesYour boiler is unable to safely breathe because the pipes that bring in fresh air or take away exhaust fumes are blocked or restricted.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flue and/or air supply duct is blocked.
What causes this fault?
This fault occurs when the boiler's internal sensors detect that air cannot flow freely through the system to support safe combustion. It is usually caused by an external obstruction in the flue pipe, a buildup of debris, or a mechanical failure in the fan that pushes the exhaust gases out of your home.
This fault is more common during autumn and winter, as falling leaves or nesting birds can block the external flue terminal, and heavy snow can obstruct the air intake.
DIY fix possible
Check the external flue pipe on the outside of your property for obstructions like bird nests, leaves, or debris.Ensure there are no items like garden furniture or storage boxes blocking the flue terminal.If it is snowing, gently clear any snow or ice buildup from the end of the pipe.
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A boiler cover plan would cover faults like F018 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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