Navien tankless water heaters display an E-code (like E003 or E110) when something interrupts safe operation. Most point to gas supply, a dirty flame sensor, or restricted air intake/exhaust — not a failed unit. Find your code below.
Codes at a Glance
| Code | Meaning | |
|---|---|---|
| E003 | Ignition failure | Full guide → |
| E012 | Flame loss during operation | Full guide → |
| E016 | Overheat protection tripped | Full guide → |
| E110 | Air pressure / exhaust blockage | Full guide → |
| E351 | Water flow sensor fault | Guide coming soon |
| E438 | Recirculation-related fault | Guide coming soon |
| E515 | PCB / grounding fault | Full guide → |
FAQ
How do I clear a Navien error code?
Fix the underlying cause first. A straight power-cycle without addressing the cause often brings the same code right back within a heating cycle or two.
Does Navien error code history matter?
Yes — most Navien controllers store recent fault history in a menu. If a code keeps recurring, note the pattern (time of day, weather, water usage) before calling a technician; it speeds up diagnosis.
Written by HotWater Decoded — water heater repair specialists. Technically reviewed by a licensed technician on our team.
- Manufacturer PDF manuals and JustAnswer/Reddit threads
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