E09
NTI Combustion Fan Speed / RPM Fault

Boiler locks out with E09; may indicate fan speed or RPM error on display

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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

Failed combustion fan motor, Blocked fan wheel, Faulty fan speed feedback (Hall sensor), Loose fan connector at control board

How to Fix / Troubleshooting

Safety: Disconnect power before removing the fan assembly. Sharp metal edges may be present.

  • Visual inspection: Remove the front cover and locate the combustion fan. Check for debris, broken blades, or signs of overheating.
  • Spin test: With power off, rotate the fan wheel by hand. It should spin freely without grinding. If stiff or seized, the fan assembly must be replaced.
  • Check wiring: Ensure the multi‑pin connector from the fan to the control board is fully seated and not corroded.
  • Operational test: Restore power and call for heat while observing the fan. If it hums but does not reach speed, or speed fluctuates, a technician should test supply voltage and replace the fan if defective.
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Repair Difficulty

Hard 4/5

Required Part

Combustion Fan Assembly
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