Boiler reports a flue gas recirculation or flue system fault; may shut down shortly after ignition.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety: Turn off the boiler and do not operate it if a flue fault is suspected. Flue gas recirculation can lead to carbon monoxide hazards.
User‑level checks:
- From outside, visually inspect the flue terminal for obstructions and ensure required clearances from walls, windows, and vents are maintained.
- Check that any flue terminal guards are not blocked with debris.
Professional actions: A Gas Safe engineer must inspect the entire flue system, seals, and combustion settings, and test the flue gas sensor. Do not attempt to dismantle the flue yourself.