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Navien E109 — Fan Motor Error
Your Navien flagged a problem with the combustion fan — the blower that pulls in air and pushes out exhaust. Without correct airflow, the unit can't burn safely, so it locks out.
$99 dispatch and diagnosis fee — waived if you approve the repair
The combustion fan controls the air side of combustion — drawing in fresh air and pushing exhaust out through the vent. Navien watches the fan's speed, and when it can't reach or hold the RPM the control board expects, it posts E109 and stops, because burning gas without correct airflow is unsafe.
The most common trigger is a dirty air-intake filter starving the fan of air. Beyond that it's the fan motor itself, its wiring, or the voltage the board is supplying. We start with the cheap, common causes before touching the fan.
What causes E109
1. Dirty or blocked air-intake filter
A clogged intake filter is the first thing to check — it starves the fan and skews the airflow the board expects. Cleaning it resolves a good share of E109s.
2. Worn or failing fan motor
Fan motors wear out after years of runtime. Bearings drag, RPM drops, and the board flags E109. Replacement is a defined repair.
3. Wiring or connector to the fan
A loose, corroded, or damaged connector between the fan and the control board can interrupt the RPM signal or power.
4. Control-board voltage
If the board isn't supplying correct voltage to the fan, the fan can't spin up. We measure at the board before deciding fan vs. board.
What you can safely check first
- Check and clean the air-intake filter. A clogged filter is the cheapest and most common cause.
- One reset is reasonable after cleaning the filter.
- Do not keep running the unit with a fan fault. Airflow is what makes the combustion safe.
When to stop and call us
If E109 returns after a clean filter and one reset, the fan, its wiring and the board voltage have to be tested with a meter. That is a professional diagnostic, not a parts swap.
Need Navien repair on the South Shore?
An error-code guide can explain the symptom. If your home is in Hull, Quincy or our surrounding South Shore service area, Johnson Bros. can help with the next step: diagnosing your Navien boiler, combi boiler or tankless water heater.
The house has no heat
Tell us whether every room is cold or just one heating zone, and whether the boiler display shows a code.
Boiler and no-heat repairThe taps have no hot water
Check whether it affects one fixture or every hot tap. Tell us if you have a tank, a tankless heater, or a boiler that also heats your water.
Help with no hot waterBoth stopped working
Mention both symptoms when you call, especially with a combi boiler. Have the brand, model and displayed code ready if you can read them safely.
Navien service and repairCalls are answered 24/7. Call for urgent no-heat or no-hot-water trouble; we will confirm appointment availability. Online booking does not guarantee immediate dispatch.
Local service: Hull heating repair · Quincy · Weymouth · Hingham · Braintree · Abington.
Smell gas? Leave the house first, then call the gas utility or 911 from outside. Do not use switches, phones or anything that sparks inside the building, and do not go looking for the source. Call us afterwards, once it is safe, for the repair.
Seeing E109 on your Navien?
Book online and we will diagnose the actual cause, explain what we find, and price the repair before starting.
Navien E109 FAQs
What does Navien error code E109 mean?
E109 is a combustion fan motor error. The fan moves air through the burner and pushes exhaust out the vent; when it cannot reach or hold the speed the control board expects, the unit locks out because burning gas without correct airflow is unsafe.
What causes E109?
The most common cause is a dirty air-intake filter starving the fan. Beyond that it can be a worn fan motor, a loose or corroded wiring connector, or the control board not supplying correct voltage to the fan.
Can I fix E109 myself?
You can safely check and clean the air-intake filter and try one reset. If the code returns, the fan, its wiring, or the board voltage needs to be tested with a meter — that is a professional diagnostic. Do not run the unit repeatedly with a fan fault.
How much does E109 repair cost?
The $99 service fee sends a licensed technician out to diagnose the problem. Approve the repair on the spot and the fee is not charged at all; decline it and the $99 covers the visit. If it turns out to be a filter or connector, the fix is inexpensive; a replacement fan motor is a defined part-and-labor cost we quote before proceeding.
Other codes on this unit? See all Navien error codes.
Why South Shore homeowners choose Johnson Bros.
Navien E109 diagnosed properly
We diagnose the cause rather than clearing the code and hoping. You get an upfront price before any work starts.
Not sure what's wrong? Send a photo or videoBooking online is the quickest way to hold the next open appointment. Call instead if it is urgent and you would rather talk to someone.
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Related services
All Navien error codes
The other codes this unit can show, and what each one means.
Navien service and repair
Installation, service and repair for Navien equipment on the South Shore.
Water heater repair and replacement
Repair and replacement options for tank and tankless water heaters.
Family Plan
Members get 10% off, priority scheduling, and the $99 fee waived even if you decline the quote.
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Upfront Options
You get a clear explanation of the work and price before the job begins.
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We help you understand whether repair, replacement, or follow-up service makes the most sense.
Navien E109 diagnosed properly
We diagnose the cause rather than clearing the code and hoping. You get an upfront price before any work starts.
Call for urgent help now. Book online when you want the next available fit for your schedule.