BoilerFaultCodesYour boiler's internal fan is staying on when it should be turning off, which prevents the boiler from starting its normal heating cycle.
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 computer incorrectly detects that the fan is still spinning even after it has been told to stop. The most common reason is a sticking relay on the main control board or a faulty sensor within the fan itself that is sending a false signal, which prevents the boiler from safely starting the next ignition sequence.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like C4 — no call-out fees, no surprises.
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