Navien
-
⛔ Do Not Use
Navien - Error Code E109
Navien Water Heater error code E109: Exhaust blockage / restricted flue.
Is it safe?
⛔ No — stop using
Do NOT operate — potential gas or CO hazard. Ventilate the area and call a technician immediately.
Can I fix it?
Technician Required
Repair cost
Pro: $150–$600
⏱ 1–3 hours (pro)
What Does Error Code E109 Mean?
Navien Water Heater error code E109: Exhaust blockage / restricted flue.
Part that typically fails: Gas valve / igniter / heat exchanger
Do NOT operate — potential gas or CO hazard. Ventilate the area and call a technician immediately.
Symptoms You May Notice
- ⚠️ Error code on display
- ⚠️ No hot water
- ⚠️ Water heater shutting down unexpectedly
What the Technician Will Do
🔧 Professional repair required. Do not attempt DIY — this repair requires specialized tools or certification.
- 1 Check your owner's manual for model-specific guidance on error code reset procedures
- 2 If the error persists after reset and basic checks, contact a qualified technician
⚡ Quick tip: Always try a full power reset first — turn the unit off at the breaker, wait 30 seconds, restore power.
Frequently Asked Questions
What does Navien Water Heater error code E109 mean? ▼
Error code E109 on a Navien tankless water heater indicates: Exhaust blockage / restricted flue. The unit has detected this condition and has limited or stopped operation to prevent further damage.
How do I fix Navien Water Heater error code E109? ▼
Start by powering the unit off for 30 seconds and restarting. If error E109 returns, the underlying cause (exhaust blockage / restricted flue) needs to be addressed. Check wiring connections and filters first before replacing components.
Is Navien error code E109 serious? ▼
It depends on the root cause. Some E109 errors resolve with a reset. Others indicate a failed component that requires professional repair. Don't continue operating with this error — it can lead to further damage.