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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.
What E109 Means
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.
Common Causes of 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.
E109 FAQs
Why South Shore homeowners choose Johnson Bros.
Navien showing E109? We start with the cheap fixes first.
Often it's just a clogged intake filter. Tell us your model and we'll walk it from there.
Need help fast? Call for urgent plumbing issues. Booking online is best when you want the next open appointment without waiting on the phone.
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Navien showing E109? We start with the cheap fixes first.
Often it's just a clogged intake filter. Tell us your model and we'll walk it from there.
Call for urgent help now. Book online when you want the next available fit for your schedule.