E9
Peerless
Communication Error / Internal Control Failure
Boiler control shows E9 and will not respond to thermostat calls
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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
Faulty control board, loose harness between display and main board, electrical noise or grounding issue
How to Fix / Troubleshooting
Safety first: Turn off power at the breaker or service switch before opening the control panel.
Steps:
- Inspect control wiring: Remove the front cover and check the ribbon cable or harness between the user interface/display and the main Peerless control board. Reseat connectors.
- Check grounding: Verify the boiler is properly grounded and that neutral and ground are not reversed at the service connection.
- Look for moisture: Check for signs of water intrusion or condensation on the control board. Correct any leaks from piping or relief valves.
- Power cycle: Restore power and see if the code clears after a full reboot.
- If E9 remains: The control board or display module may need replacement. This should be done by a qualified technician to ensure correct programming and safety checks.
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Repair Difficulty
Hard
4/5
Required Part
Boiler control board
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