BoilerFaultCodesTechnical description
Differential air pressure switch open, Fan - off
What causes this fault?
This fault occurs when the boiler's internal safety sensor cannot detect the necessary airflow required to safely expel exhaust gases. It is usually caused by a failing fan motor that isn't spinning fast enough, a perished rubber tube, or a blockage within the flue pipe itself.
This issue can be more frequent during periods of high winds, as strong gusts can create back-pressure in the flue that prevents the pressure switch from closing correctly.
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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