E450
Lennox
Zoning System Communication / Configuration Error
Thermostat shows E450; furnace may not operate in certain modes or may lock out.
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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
Miswired Lennox zoning panel, Incorrect zone configuration, Faulty zone control board, Communication cable issues between furnace and zone panel
How to Fix / Troubleshooting
Safety: Turn off power to furnace and zoning panel.
- 1. Inspect zone panel wiring: Verify that R, C, W, Y, G, and communication terminals between the Lennox furnace and zone panel are correctly wired per the Lennox zoning manual.
- 2. Check zone dampers: Ensure damper wiring is intact and that no damper is stuck closed, causing airflow issues.
- 3. Verify configuration: Confirm the number of zones and equipment type are correctly set on the zone panel DIP switches or programming.
Zoning issues can cause comfort and equipment problems; a Lennox-trained technician should finalize diagnosis if E450 remains.
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Repair Difficulty
Hard
4/5
Required Part
Lennox Zone Control Board
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