BoilerFaultCodesTechnical description
Blocked flue/air intake (high resistance)
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the fan is unable to push exhaust gases out of the flue or pull in enough oxygen for combustion. The most common reasons include a physical obstruction in the external pipework, such as a bird's nest or debris, or a mechanical failure of the fan itself which prevents it from reaching the necessary speed.
This fault is slightly more common during autumn and winter, as fallen leaves or nesting birds can cause blockages in the flue outlet.
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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