Navien E109: Combustion-Fan Fault
What the Navien E109 error code means, what causes it, and why it's a job for a licensed BC gas technician — not a DIY reset.
Severity
High — needs prompt professional attention
Gas safety first
This fault involves gas, combustion or venting. If you smell gas (rotten-egg odour), hear hissing, or feel unwell, leave the building immediately and call 911 or FortisBC at 1-800-663-9911 from outside. Do not flip switches or relight anything. For all other cases, switch the boiler off and call a licensed gas technician.
What the Navien E109 error code means
The combustion fan is not running at the speed the control expects, so ignition is blocked for safety.
On Navien NCB-E, NCB-H, NHB, NFB and NPE-A2 series, E109 is a combustion-fan fault. It is a protective response — the boiler is telling you something needs attention, and the safe, lasting fix is a proper diagnosis rather than repeated resets.
Symptoms you may notice
- No heat or hot water
- Boiler will not begin its ignition sequence
- Unusual fan noise or no fan sound at all
Common causes of Navien E109
Why this is not a DIY fix
The combustion fan controls the air–gas ratio. A fan or fan-speed-feedback fault means the boiler cannot prove safe airflow, so it (correctly) refuses to fire. Replacing and re-commissioning the fan involves combustion verification — licensed gas work.
In British Columbia, gas work must be performed by a TSBC-licensed gas fitter. GasBoilers.ca — a CanroHeat division — sends Red Seal–certified, gas-licensed technicians who diagnose the true cause, repair it correctly, and verify safe operation before they leave.
How our technicians diagnose & repair it
- 1Test fan power, speed feedback (Hall sensor) and wiring
- 2Inspect the fan and venturi for debris, dust or seized bearings
- 3Check the control board fan-drive output
- 4Replace the fan if needed and re-run combustion analysis
Related Navien codes
Navien E109 — FAQ
What does the Navien E109 error code mean?
The combustion fan is not running at the speed the control expects, so ignition is blocked for safety. On Navien NCB-E, NCB-H, NHB, NFB and NPE-A2 series, this is categorised as a combustion-fan fault.
What causes Navien E109?
The most common causes are: Failed fan motor or bearing; Fan speed-feedback (Hall) fault; Debris in fan/venturi; Wiring or board output fault. A licensed technician confirms which one applies before any part is replaced.
Can I fix Navien E109 myself?
No. The combustion fan controls the air–gas ratio. A fan or fan-speed-feedback fault means the boiler cannot prove safe airflow, so it (correctly) refuses to fire. Replacing and re-commissioning the fan involves combustion verification — licensed gas work. Repeatedly resetting the boiler without fixing the root cause can be unsafe and can cause further damage. Call GasBoilers.ca at 604-359-1081 for a licensed diagnosis.
Is the Navien E109 error code dangerous?
It can be. This fault involves combustion, gas or venting. If you ever smell gas, leave the building immediately and call 911 or FortisBC at 1-800-663-9911 from outside. Otherwise, switch the boiler off and book a licensed technician.
How much does it cost to fix Navien E109 in Greater Vancouver?
Cost depends on the root cause and any parts needed. We start with a flat-rate diagnostic, then quote the repair before any work begins — no surprises. Call 604-359-1081 for current pricing and same-day availability.
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