BoilerFaultCodesYour boiler has detected a problem with how it disposes of waste gases, which has caused it to shut down 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: Fault on Fan or Flue
What causes this fault?
This fault occurs when the boiler's safety system detects that the fan isn't moving enough air to safely vent exhaust gases out of the flue. The most common reasons are a build-up of dirt in the fan or small tubes, a mechanical failure of the fan motor, or an electrical fault where the control board can no longer communicate with the air sensors.
This issue can occasionally follow periods of high winds or heavy rain, which may cause debris or moisture to interfere with the delicate sensors and tubes connected to the flue.
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 25 — 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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