Boiler shows E17, may indicate ionisation current out of range or unstable flame

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

Incorrect gas pressure, Partially blocked burner, Poor flue draught, Faulty flame electrode

Safety first: Turn off gas and power. Combustion adjustments must be done by a Gas Safe engineer.

Check flue terminal: Ensure adequate clearance around the flue terminal and no obstructions.
Engineer combustion check: The engineer should measure inlet gas pressure, burner pressure, and flue gas composition. Adjust or repair as necessary.
Clean burner and electrode: Remove and clean the burner and flame electrode, removing any debris or corrosion.
Check earthing: Verify good earth continuity to improve flame signal stability.

Professional Required 5/5

Burner and Flame Electrode

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