BoilerFaultCodesTechnical description
Poor combustion – flue terminal may be blocked
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the gas isn't burning cleanly or safely. The most common reason is a physical obstruction in the flue pipe outside, but it can also be caused by an incorrect mixture of gas and air during the ignition process. To protect you from carbon monoxide, the system automatically shuts down when it detects these poor combustion levels.
This fault is more common during autumn and winter, as fallen leaves or heavy snow can easily block the external flue terminal.
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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