BoilerFaultCodesTechnical description
Fault indication / Lockout reset button
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the exhaust gases are not being cleared from the system effectively. The most common reasons include a physical obstruction in the external flue pipe, such as a bird's nest or debris, or a mechanical failure of the fan that pushes these gases out. Because these gases are dangerous, the boiler will immediately stop working as a safety precaution.
This issue is slightly more frequent in winter as high winds can cause pressure fluctuations in the flue, or heavy snowfall can physically block the external 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.