BoilerFaultCodesYour boiler has shut down because it is unable to safely discharge exhaust fumes or has detected that the flue system is overheating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Lockout due to flue thermostat or pressure switch
What causes this fault?
This fault occurs when the boiler's internal sensors detect that harmful exhaust gases are not being cleared away correctly or that the flue is getting too hot. The most common reasons include a blockage in the flue pipe, a failing fan that cannot push the fumes out, or a sensor that has become faulty and is giving a false reading.
This fault can sometimes occur during period of high winds, as strong gusts can create back-pressure in the flue that interferes with the air pressure switch.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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