BoilerFaultCodesYour boiler has detected that its internal fan is spinning at the wrong speed, which means it cannot safely exhaust fumes and has stopped working as a result.
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 high
What causes this fault?
This fault occurs when the boiler's control system loses the ability to regulate the fan speed effectively, often due to a mechanical failure or an electrical communication error. The most common reason is a failing fan motor or a fault within the main circuit board that prevents it from sending the correct signals to manage airflow.
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 C6 — no call-out fees, no surprises.
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