BoilerFaultCodesYour boiler is trapped in a cooling-down cycle where the fan keeps running longer than necessary, preventing it from starting a new 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: Heating system fan over run
What causes this fault?
This fault occurs when the boiler's control board fails to receive a signal that the fan has slowed down or stopped after a heating cycle, causing it to stay in a permanent cooling mode. The most common reason is a malfunctioning relay on the main circuit board or a faulty fan that is sending incorrect speed data back to the system. While the boiler is stuck in this 'over run' phase, it will refuse to ignite for central heating or hot water because it believes it hasn't finished cooling down.
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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