E12
Triangle Tube
Control Board Communication Fault
Boiler shows E12, communication error between display and main control
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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
Loose low-voltage harness between user interface and main board, Electrical noise or power surge damage, Failed display board, Failed main control board
How to Fix / Troubleshooting
Safety: Turn off power before accessing the control compartment.
- Step 1 – Reseat connectors: Open the front panel and locate the communication cable between the Triangle Tube boiler’s main control board and the display/interface. Unplug and firmly reconnect both ends.
- Step 2 – Inspect cable: Look for pinched, cut, or burned sections of the cable. Replace if damaged.
- Step 3 – Power cycle: Restore power and see if the E12 code clears. Sometimes a full power reset will restore communication.
- Step 4 – Check grounding and power quality: Ensure the boiler is properly grounded and not sharing circuits with large motors that can cause electrical noise.
- Professional diagnosis: If E12 persists, a technician should test the boards and replace the faulty display or main control module.
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Repair Difficulty
Medium
3/5
Required Part
Main Control Board
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