BoilerFaultCodesTechnical description
Flue/Fan/Differential air pressure switch fault
What causes this fault?
This fault occurs when the boiler's safety sensors detect that the fan isn't moving enough air to safely clear exhaust gases from the flue. The most common reasons are a buildup of dirt or debris in the fan or internal tubes, a failing fan motor, or a blockage within the flue pipe itself. To protect you from carbon monoxide, the boiler will not attempt to ignite until this airflow is restored.
This issue can be more common during periods of high winds, which can create back-pressure in the flue and disrupt the sensitive air pressure readings.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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