BoilerFaultCodesYour boiler has detected that a safety sensor is stuck in the wrong position, preventing the fan from starting up correctly to clear waste gases.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Air pressure switch error – contacts closed on activation of fan
What causes this fault?
This fault occurs when the boiler's safety system detects that the air pressure switch is already 'on' before the fan has even started. This usually happens because the internal mechanism of the switch is physically stuck or there is moisture trapped in the small plastic sensing tubes. Because the boiler cannot verify that the fan is working safely, it prevents the ignition process from starting.
This issue can be more frequent during periods of heavy rain or high humidity, as moisture and condensation can collect inside the air pressure sensing tubes.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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