BoilerFaultCodesYour boiler's fan is running constantly and won't shut down, preventing the system from finishing its normal cycle or restarting correctly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Fan does not switch off.
What causes this fault?
This fault occurs when the boiler's control system detects that the fan is spinning continuously even when it should be at rest. The most common reason is a mechanical failure within the fan itself or a communication error from the main circuit board that keeps the power running to the motor constantly.
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 C4 — no call-out fees, no surprises.
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