Navien Boiler and Tankless Error Codes Explained
Navien is the leading brand of condensing tankless water heaters and combination boiler systems in North America, known for high efficiency and advanced diagnostics. When a Navien NCB, NHB, NFB, or NPE series unit develops a fault, it displays a specific error code on the front panel that tells you exactly what went wrong. This guide explains the most common Navien error codes and what you need to do about them.
How Navien Error Codes Work
Navien units display error codes directly on the front-panel LCD. The code appears with a short description (e.g., "E003: Ignition Failure"). Many Navien units also log fault history accessible through the service menu. NaviLink Wi-Fi modules allow fault codes to be viewed and cleared remotely through the NaviLink app, which also sends push notifications when an error occurs.
Common Navien Error Codes
| Error Code | Meaning | What to Do |
|---|---|---|
| E003 | Ignition failure — no flame detected | Check gas supply; clean igniter; call tech if recurring |
| E007 | Hot surface igniter circuit fault | Technician required — igniter replacement |
| E009 | Heat exchanger outlet sensor error | Technician required — sensor replacement |
| E010 | Abnormal temperature at heat exchanger | Check for scale buildup; technician for descaling |
| E011 | Heat exchanger inlet sensor fault | Technician required |
| E012 | Flame loss during operation | Check gas pressure; call technician |
| E016 | Overheating — high limit trip | Check water flow rate; call technician |
| E030 | Exhaust temperature too high | Check vent for blockage; call technician |
| E046 | False flame detected | Technician required — flame sensor or gas valve |
| E109 | Abnormal fan speed | Technician required — fan motor or board |
| E110 | Exhaust or intake blockage / vent fault | Check exterior vent termination for blockage |
| E302 | Low water pressure (combi/boiler models) | Check system water pressure; add water if low |
| E351 | DHW flow sensor fault | Technician required — sensor replacement |
E003 Ignition Failure: Most Common Navien Code
E003 is the most frequently reported Navien error. It means the unit attempted to ignite and failed. Common causes include: low gas pressure (check other appliances), a dirty or failed igniter, a clogged condensate drain preventing safe operation, or a restricted vent. If you see E003 during extremely cold weather, check the exterior vent termination for ice blockage — this is a known issue with Navien units during Wisconsin winters. The PVC vent terminations can ice over, causing ignition failures.
E110 Exhaust/Intake Fault: Cold Weather Check
E110 indicates the unit detected an issue with the exhaust or intake. In winter, this is almost always ice forming at the vent termination on the exterior of the home. Carefully remove ice from around the vent opening — do not block the vent and do not use sharp tools that could damage the PVC pipe. After clearing, reset the unit. If E110 continues to recur in cold weather, a technician can install proper vent termination extensions or deflectors to prevent ice buildup.
Scale Buildup and E010/E016
Navien units in areas with hard water (which includes much of Southeastern Wisconsin) are susceptible to scale buildup inside the heat exchanger. This reduces flow and efficiency, eventually triggering E010 or E016 (overheating) faults. Annual descaling with a vinegar or citric acid flush can prevent this. If the heat exchanger is severely scaled, a technician will need to perform a descaling service or replace the heat exchanger.
When to Call a Professional
Most Navien error codes beyond E110 (vent blockage) and E302 (low water pressure) require professional service. Ignition system faults, sensor replacements, and gas valve issues should be diagnosed by a technician familiar with Navien's condensing combustion systems. Navien systems are more complex than standard boilers and require specific training to service properly.
Burkhardt Heating, Cooling, Plumbing & Electric services Navien boiler and tankless systems throughout Southeastern Wisconsin. We stock common Navien repair parts and provide 24/7 emergency service.
Navien Service and Repair in Wisconsin
Navien error codes are specific — they tell you and your technician exactly what the unit detected. That diagnostic precision typically means faster, more accurate repairs and a lower total service bill.
If you see any of these codes, call Burkhardt at 414-206-3049. Our NATE-certified technicians can diagnose and repair the issue — usually in a single visit.
Ready to schedule service? Call Burkhardt Heating, Cooling, Plumbing & Electric at 414-206-3049 or contact us online. Available 24/7 for emergencies.
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