BoilerFaultCodesYour boiler has stopped working because the pipe that lets exhaust gases out is blocked or the internal sensor that checks for airflow is clogged with dirt.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Debris in flue system, Debris in flue venturi. Boiler or flue system has developed a fault.
What causes this fault?
This fault occurs when the boiler's safety sensors detect that harmful exhaust gases are not being cleared from the system correctly. The most common cause is a buildup of dust or debris inside the small tubes that monitor airflow, or a mechanical failure in the fan that pushes the gases outside.
This fault often occurs during periods of high wind, which can create back-pressure in the flue and trigger the sensitive air pressure switch.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like 03 — no call-out fees, no surprises.
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