BoilerFaultCodesTechnical description
Flue gas/DAPS (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 air effectively or that exhaust gases are not being safely cleared through the flue pipe. The most common reason is a blockage in the small plastic tubes inside the boiler, a failing fan motor, or debris obstructing the air passage from outside.
This fault is more common during periods of high winds, which can create back-pressure in the flue that prevents the air 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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