Boiler displays F7, often related to flue gas sensor or temperature sensor issues on condensing models.
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 first: Turn off power. Flue components are part of the combustion circuit and must be handled by qualified engineers.
Homeowner checks:
- Visually check the flue terminal outside for obstructions.
- Reset the boiler once; if F7 returns, call an engineer.
Engineer checks:
- Test the flue gas sensor resistance and compare with Worcester specifications.
- Inspect wiring and connectors for heat damage or corrosion.
- Check flue for partial blockage or incorrect installation causing high flue temperatures.
- Replace the flue gas sensor if readings are incorrect.
Flue gas temperature monitoring is a safety function; do not bypass or ignore this fault.
Repair Difficulty
Required Part
We may earn a commission from links on this page.