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Navien E109 Error Code: Combustion Fan Fault

Abnormal fan operation — the combustion fan is not running at commanded speed.

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Call (408) 470-0191Get this diagnosed

Open 24/7 · CSLB #1008381 · Joseph J. Castro, Owner

Navien tankless water heater control panel showing error code E109

Quick answer

Navien E109 means: Abnormal fan operation — the combustion fan is not running at commanded speed. It's usually caused by failing fan motor, debris in the blower, or a wiring/board fault. The fix: Test fan feedback signal, clean or replace the fan assembly, and confirm normal combustion afterward. Efficient Water Heaters, Inc. diagnoses Navien E109 faults across San Jose 24 hours a day, 7 days a week — (408) 470-0191, CSLB #1008381.

What you'll notice with E109

  • Grinding, whining, or rattling from inside the cabinet
  • Unit won't start a heating cycle at all
  • Intermittent lockouts that clear on their own for a while

What causes it

Failing fan motor, debris in the blower, or a wiring/board fault.

Safe steps you can take right now

  1. 1Listen for debris noise; a garage install can pull in a surprising amount.
  2. 2Power cycle once — a stuck fan sometimes clears.
  3. 3Schedule service; a failing fan will strand you eventually.

How we fix E109

We read the fan's speed feedback signal against the commanded value, inspect the blower wheel for debris and bearing wear, and check the harness and board output before condemning the motor.

Test fan feedback signal, clean or replace the fan assembly, and confirm normal combustion afterward.

Get your Navien E109 fixed

Call (408) 470-0191 any hour, or send the form and we'll reach out.

Send a photo of your data plate for a faster estimate.

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Navien E109 questions

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Navien E109 — related services, cities, and codes

E109 rarely shows up alone. These are the services that resolve it, the cities we cover, and the codes that often appear alongside it.