BoilerFaultCodesYour boiler is having trouble venting exhaust gases safely, which prevents it from firing up to provide heating or hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: APS / FAN ALARM
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the fan isn't moving enough air to safely clear exhaust gases from the system. It is usually caused by a failing fan motor, a blockage in the air pressure tubes, or debris caught in the flue that prevents a steady flow of air. Without this confirmed airflow, the boiler won't ignite to ensure carbon monoxide doesn't build up inside the unit.
This fault is slightly more common in autumn and winter, as high winds can cause back-pressure in the flue or debris like fallen leaves can block the external air intake.
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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