Navien Error Code E110: Exhaust Blocked
How to Fix Navien Code E110
- Step 1: Check the outside exhaust vent terminal—clear away any snow, ice, leaves, or debris. Do not remove the vent pipe.
- Step 2: Press the reset button on the unit once (if equipped). If the code returns immediately, do not keep resetting.
- Step 3: If the outside vent is clear and the code returns, call a qualified Navien technician—do not attempt to disassemble the exhaust system yourself.
How to Reset Navien Code E110
- 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 E110 Mean?
The E110 code on a Navien unit means the control board detected that exhaust gases are not flowing properly out of the flue pipe. This can be because the exhaust pipe is blocked by debris, snow, or ice, or because the combustion fan cannot push the gases out due to a restriction. The unit shuts down to prevent carbon monoxide from backing into the home. This code is common on condensing models where the plastic exhaust vent can become clogged with ice in winter or with debris over time. Do not attempt to operate the unit until the blockage is cleared, and always have the vent system inspected annually.
Common Causes
- Exhaust vent terminal blocked by snow, ice, or debris (most common in winter)
- Obstruction inside the exhaust pipe (bird nest, rodent, dirt)
- Failed combustion fan motor or blocked fan inlet
- Condensate trap or drain line plugged causing backpressure in the heat exchanger
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Unit shows E110 and exterior vent is buried in snow | Clear snow from vent terminal | Code resets and unit runs normally |
| Outside vent is clear but code returns | Inspect exhaust pipe for obstructions using a camera or by disconnecting at the unit | Clean, unobstructed pipe |
| Pipe is clear, code still active | Measure resistance of combustion fan motor at the harness connector | 20-100 ohms depending on model |
| Fan resistance normal, code persists | Check condensate trap and drain line for blockages | Free-flowing condensate, no standing water in trap |
Applicable Navien Models
Source Documentation
Referenced in 5 official Navien technical manuals.
| Manual | Page | Reason | Action |
|---|---|---|---|
| NFB-H Installation & Operation Manual | 116 | Exhaust Blockage | Check exhaust venting. |
| Navien NCB-H Installation & Operation Manual | 129 | Exhaust Blockage | ● Ensure that the exhaust pipe is free of obstructions. ● Clean the intake air filter. |
| Navien NFB-H Installation & Operation Manual | 116 | Exhaust Blockage | Check exhaust venting. |
| Navien NFC-H Installation & Operation Manual | 127 | Abnormal air pressure | Manual RESET |
| Navien NHB-H Installation & Operation Manual | 119 | Exhaust Blockage | Check exhaust venting. |
Recall Notices
Issued: December 20, 2018
Affected models: NPE-180A, NPE-180S, NCB-180E manufactured July 9 - October 14, 2018
LP gas conversion kits can cause units to produce excessive carbon monoxide.
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Combustion Fan Assembly | 30023130A | — | Find Part |
| Exhaust Vent Termination Kit | — | — | — |
| Condensate Trap Assembly | 30026873A | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Navien model families as E110.
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E012 | Flame Loss | Warning |
| E016 | Overheating | Warning |
| E030 | Exhaust Overheat Sensor | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E047 | DHW Thermistor Open/Short | Warning |
| E060 | Fan Motor Abnormality | Warning |