BoilerFaultCodesYour boiler has detected an issue with how it clears fumes from the system, preventing it from lighting safely for your heating and hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Fan or Air Pressure Switch fault (Dip-switch #3 in off position).
What causes this fault?
This fault occurs when the boiler's internal safety sensors fail to detect the correct airflow required to safely expel exhaust fumes. The most common reasons are a buildup of dirt in the fan or air tubes, or a mechanical failure in the fan itself that prevents it from reaching the necessary speed. Because the boiler cannot confirm that the area is clear of waste gases, it shuts down for your safety.
This fault is more common during the autumn and winter months when birds nesting or debris from bad weather can cause blockages in the external flue pipe.
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 LED 1 on, LED 2 flashing — no call-out fees, no surprises.
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