Err 11
Burnham Air Proving or Fan Speed Fault

Boiler display shows “Err 11” and burner does not light, fan may run briefly

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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

Inducer fan speed out of range, Blocked or restricted combustion air path, Faulty fan speed sensor or Hall sensor, Loose fan wiring connector

How to Fix / Troubleshooting

Safety first: Turn off power and gas. Venting issues can be hazardous.

  • Inspect inducer fan: Remove the front cover and visually inspect the combustion fan. Check for dust buildup, debris, or signs of water intrusion from condensate.
  • Check fan wiring: Ensure the multi-pin connector from the fan to the control board is fully seated and free of corrosion.
  • Verify vent and intake: Confirm that vent and intake pipes are clear and properly supported. Sagging pipes can collect condensate and restrict flow.
  • Reset and test: Restore power and call for heat. Listen for abnormal fan noises. If Err 11 returns, the fan assembly or its speed sensor may need replacement by a technician.
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Repair Difficulty

Hard 4/5

Required Part

Combustion Fan Assembly
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