E11
NTI
Control Board Communication / Internal Fault
Boiler displays E11; no response to thermostat call; control appears unresponsive or frozen
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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
Defective main control board, Corrupted firmware, Shorted low‑voltage wiring (thermostat, outdoor sensor, bus), Electrical surge damage
How to Fix / Troubleshooting
Safety: Turn off power at the breaker before touching any control wiring.
- Power cycle: Turn off power for at least 60 seconds, then restore. Observe if the E11 clears temporarily.
- Inspect low‑voltage wiring: Check thermostat, outdoor sensor, and any bus connections for shorts, crushed cables, or incorrect polarity. Disconnect external controls one by one to see if the error clears.
- Check board for damage: Look for burn marks, swollen components, or corrosion on the NTI control board. If present, the board must be replaced.
- Firmware/board replacement: Control board replacement and firmware updates should be performed by an NTI‑trained technician to ensure compatibility and safe operation.
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Repair Difficulty
Professional Required
5/5
Required Part
Main Control Board
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