E04
Riello
Flue Gas / Draft Fault
Display shows E04, indicating flue gas or draft fault
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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.
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Possible Causes
Blocked chimney or vent, Failed draft inducer fan, Faulty flue gas thermostat or pressure switch, Poor combustion causing high flue temperature
How to Fix / Troubleshooting
Safety: Turn off power and fuel. Do not operate the furnace with a suspected flue blockage—risk of CO exposure.
Steps:
- Inspect venting: Check the vent pipe and chimney for obstructions, corrosion, or disconnections. Clear any blockage.
- Check draft inducer: Verify the inducer fan runs and the wheel is clean. Replace if seized or noisy.
- Test flue safety devices: Check continuity of flue gas thermostat or pressure switch when cool. Replace if open when it should be closed.
Flue and combustion issues should be evaluated by a qualified technician with proper test instruments.
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Repair Difficulty
Professional Required
5/5
Required Part
Flue Gas Thermostat
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