Navien Tankless Error Codes: What They Mean & What to Do
Your Navien is showing an E code. Here’s what the most common ones mean and what to do next.
Updated October 2026 · By the Hot Water Heater Factory team
Navien error codes and what they mean
| Code | What it means | What to do |
|---|---|---|
| E003 | Ignition failure | Make sure the gas is on, then text us. |
| E004 | False flame detected | A technician needs to check this. Text us the code. |
| E012 | Flame loss during operation | Often low gas supply or venting. Text us the code. |
| E016 | Heat exchanger overheating | Don’t keep resetting it. Often scale buildup; the unit may need descaling. |
| E030 | Exhaust temperature too high | Turn the unit off. A technician needs to check this. Text us the code. |
| E109 | Fan motor fault | A technician needs to check this. Text us the code. |
| E110 | Air pressure or vent blockage fault | Check the outside vent for blockages, then text us. |
These are the most common codes on Navien NPE tankless water heaters. Navien uses different codes on different series, so check your owner’s manual, or text us the code and model number.
What should I do when my Navien shows a code?
- Write down the code. If it shows more than one, note each one.
- Turn off the hot water taps. Some codes clear when the unit is turned off and back on, but if the code comes back, the unit is telling you something.
- Don’t keep resetting codes for overheating, flame or gas problems.
- Text us the code and a photo of the label. We’ll tell you what it likely means and bring the right parts.
Other brands: Rinnai codes · Noritz codes · Takagi codes. Many codes come from scale buildup; see tankless descaling and maintenance.
Questions we hear a lot
What does E003 mean on a Navien?
Ignition failure. The burner didn’t light. Common causes are the gas being off or low, air in the gas line, a venting problem or an ignition part. Check that the gas is on, then text us.
What does E016 mean on a Navien?
The heat exchanger overheated and the unit shut down to protect itself. Scale buildup and low water flow are common causes. Don’t keep resetting it.
My Navien code isn’t listed. What should I do?
Text us the code and the model number from the label. Navien codes vary by series, and we’ll tell you what yours means.
Navien showing a code? Text us now.
Send a photo of your water heater’s label and tell us what’s happening. A real person texts you back.