Navien Error Code E109: Fan Motor Speed Low
Warning: Your Navien boiler's fan motor is running slower than normal, which could lead to system issues. It's safe to troubleshoot, but call a pro if needed.
How to Fix Navien Code E109
- Check if the fan is making unusual noises. If it's loud or grinding, it might need professional attention.
- Turn off the boiler and check the fan blades for dirt or debris. Clean them gently with a soft brush if you can, but don't force anything.
- If the fan seems clean and quiet, and you're comfortable doing so, check the wiring connections. Tighten any loose screws, but don't force them.
How to Reset Navien Code E109
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Navien Error Code E109 Mean?
The E109 error on your Navien boiler indicates that the fan motor speed is lower than it should be. This could be due to a problem with the motor itself, or an issue with the control board that's regulating its speed. The fan helps to circulate air around the heat exchanger, so if it's not working properly, your boiler might not heat your home as efficiently as it should.
Common Causes
- Worn-out fan motor
- Faulty control board
- Clogged or dirty fan
- Loose or damaged wiring
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Boiler is running but not heating | Fan motor RPM using a tachometer | Around 1200-1300 RPM |
| Fan motor RPM is low | Fan motor resistance with a multimeter | Around 10-15 ohms |
Applicable Navien Models
Source Documentation
Referenced in 6 official Navien technical manuals.
| Manual | Page | Reason | Action |
|---|---|---|---|
| NFB-H Installation & Operation Manual | 116 | Abnormal Fan Motor | Check fan and venting. |
| Navien NCB-H Installation & Operation Manual | 129 | Abnormal Fan Motor | Clean the intake air filter. |
| Navien NFB-H Installation & Operation Manual | 116 | Abnormal Fan Motor | Check fan and venting. |
| Navien NFC-H Installation & Operation Manual | 127 | Abnormal operation: fan motor | Manual RESET |
| Navien NHB-H Installation & Operation Manual | 119 | Abnormal Fan Motor | Check fan and venting. |
| Navien NPF Installation & Operation Manual | 126 | Abnormal inducer fan operation | This error occurs when the fan’s RPM is abnormal. ● Turn off the furnace, turn it on again and check if the furnace operates properly. ● If the furnace is continuously inoperable, contact Technical Support at 1-800-519-8794. |
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Fan Motor Assembly | 9110110000 | — | Find Part |
| Control Board | 9110120000 | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Navien model families as E109.
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E110 | Exhaust Blocked | Warning |
| E205 | Water Flow Sensor Failure | Warning |
| E517 | Water Flow Switch Failure | Warning |
| E736 | CH Return Thermistor Failure | Warning |
| E740 | CH Buffer Tank Thermistor | Warning |