BoilerFaultCodesYour boiler has stopped working because the internal fan, which clears away exhaust fumes, is not spinning at the correct speed.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Fan speed too low.
What causes this fault?
This fault occurs when the boiler's control system detects that the internal fan isn't rotating fast enough to safely expel exhaust gases. It is usually caused by a build-up of dust on the fan blades, a failing motor, or a communication issue from the main control board. If the fan cannot reach the required speed, the boiler will shut down as a safety precaution to prevent fumes from staying inside the unit.
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 C1 — no call-out fees, no surprises.
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