E11
Dettson Communication / Control Board Fault

Boiler displays E11 and will not respond to thermostat or control inputs

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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

Internal Dettson control board failure, Loose low-voltage wiring, Shorted external control circuit, Power supply instability

How to Fix / Troubleshooting

Safety: Turn off power before accessing the control compartment.

  • Power cycle: Turn off the boiler at the service switch or breaker for 2–3 minutes, then restore power. Observe if E11 clears.
  • Check low-voltage wiring: Inspect thermostat, zone control, and communication wiring connected to the Dettson boiler control. Look for shorts, crushed cables, or loose terminals.
  • Isolate external controls: Temporarily disconnect external control circuits (following the manual) and see if the boiler boots without E11. If it does, the issue may be in external wiring or devices.
  • Board inspection: Look for burn marks, swollen capacitors, or water damage on the control board. Do not attempt board-level repair.
  • Professional replacement: If E11 persists, the Dettson boiler control board likely needs replacement and reconfiguration by a qualified technician.
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Repair Difficulty

Professional Required 5/5

Required Part

Dettson boiler control board
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