Boiler displays E20, burner stops, and the flue gas analysis test mode may not function correctly.
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: Combustion adjustments must only be made by qualified technicians with flue gas analysers. Incorrect settings can produce dangerous CO levels.
User-level actions:
- 1. Reset boiler: Perform a full reset and avoid using any test or service modes.
- 2. Check flue terminal: Ensure the flue outlet is not obstructed and that air inlets are clear.
Professional actions: A technician will clean the burner and venturi, verify fan speed, and adjust or replace the gas valve as needed while monitoring combustion values.
Repair Difficulty
Required Part
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