BoilerFaultCodesYour boiler has stopped working because it cannot safely clear away waste gases, likely due to an issue with the air fan or the exhaust vent.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Fault on Fan or Flue
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the fan isn't spinning fast enough or the exhaust pipe is blocked. Because the boiler cannot safely expel harmful waste gases, it will automatically shut down to prevent them from entering your home. Common causes include a seized fan motor, a buildup of dirt in the air tubes, or a physical obstruction in the flue pipe outside.
This fault can be more common during periods of high winds, which can create back-pressure in the flue and interfere with the air pressure sensor's 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 26 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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