Boiler indicates a flue gas temperature too high; may shut down during operation.
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 power and gas. High flue temperatures can damage the boiler and flue and may indicate combustion issues.
User checks:
- Ensure radiators and valves are open to allow adequate flow.
- Check system pressure and top up if low.
- Visually inspect the outside flue terminal for obstructions.
Professional tasks: A heating engineer should check the flue gas sensor, clean or replace the primary heat exchanger if blocked, verify pump performance, and inspect the flue system.
Repair Difficulty
Required Part
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