BoilerFaultCodesYour boiler is struggling to breathe properly because there is a blockage or too much debris in the air intake or exhaust system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Too much resistance or dirt in the air circuit; check the air supply/combustion gas discharge system, the burner, and the heat exchanger.
What causes this fault?
This fault occurs when the boiler's internal sensors detect that air cannot flow freely through the system to support safe combustion. The most common reason is a buildup of debris or soot within the heat exchanger or burner, which physically restricts the path of the gases. It can also be caused by an external blockage in the flue pipe or a failing fan that is unable to push air through the circuit effectively.
This fault often appears during the first heavy use of autumn or winter, as dust or debris settled during the summer months can be pulled into the burner when the heating starts running at full power.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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