Boiler shows F7; flame signal detected when burner should be off

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

Shorted ionisation electrode to earth, Faulty PCB flame detection circuit, Residual flame due to gas valve not closing fully, Electrical interference

Safety: Turn off gas and power immediately. Risk of uncontrolled flame if gas valve is leaking.

Reset and observe: After a short wait, restore power and see if F7 reappears without ignition attempt.
Technician tasks:
- Inspect ionisation electrode and cable for damage or short to chassis; replace if necessary.
- Check that the gas valve fully closes and that no flame remains after shutdown.
- Measure flame signal with a multimeter or service tool; if present with no flame, suspect PCB fault.
- Replace gas valve or PCB as required.

Professional Required 5/5

Ionisation Electrode

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