Navien Tankless Water Heater Error Codes: Complete NPE and NCB Series Guide

Quick Answer

Navien tankless water heaters display alphanumeric error codes when a fault is detected. Common codes include E003 (ignition failure after 3 attempts), E110 (exhaust/venting blockage), E012 (flame lost during operation), E001 (first ignition attempt failed), E302 (false flame detection), E762 (high temperature limit), and E773 (exhaust overheat). Most codes require identifying the root cause before resetting. A soft reset is done by pressing the Info button 3 times; a hard reset by cutting power for 30 seconds.

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About These Navien Waterheater Error Codes

Complete reference for all Navien NPE and NCB series error codes, including causes, diagnostic steps, and repair difficulty for each fault.

Most Common Error Codes

Blocked or kinked exhaust vent (E110, E773)40%

Ignition or flame rod failure (E003, E001)24%

Low or fluctuating gas pressure (E003, E012)14%

Electrical grounding issues (E302)12%

Scale buildup on heat exchanger (E762)10%

Symptoms You May Notice

Error code displayed on controller screen
No hot water
Unit fires then shuts off
Unusual ignition clicking sounds
Exhaust or burning smell near termination cap

Tools Required for Diagnosis

Flashlight (for inspecting vent termination)Multimeter (for electrical fault diagnosis)Screwdriver set

How to Identify Your Error Code

Note the exact error code displayed on the controller

Note the exact error code displayed on the controller. Write it down including any sub-code suffix (e.g., E110-01 vs E110-02).

Check the vent termination cap on the exterior of your home for

Verify the gas supply is fully open and other gas appliances in

Attempt a soft reset by pressing the Info button on the Navien

If reset fails, cut power to the unit at the breaker for 30

Frequently Asked Questions

How do I read the error code on my Navien water heater?

The error code is displayed directly on the digital controller screen. It will show as a letter-number combination like E003 or E110. Some codes include a sub-code suffix separated by a dash (E110-01 or E110-02) that gives more specific fault location. If the display is blank, check that the unit has power at the breaker.

Can I reset a Navien error code without fixing the problem?

You can reset it, but the code will return almost immediately if the underlying fault is still present. Repeated resets without repair can mask a worsening problem. Always identify the root cause first. The one exception is a transient fault from a power surge or brief gas interruption, where a reset after restoring normal conditions is appropriate.

What is the most common Navien error code?

E110 (exhaust blockage) and E003 (ignition failure) are the two most frequently reported codes. E110 spikes in winter when ice or condensate can block the vent termination. E003 is most common in units over 5 years old when the flame rod accumulates oxide buildup.

Do all Navien NPE and NCB models use the same error codes?

The core error code set is consistent across NPE and NCB condensing series models. There are minor differences in sub-code behavior between older NPE-A series and newer NPE-2 series, but the main codes (E003, E110, E012, E001, E302, E762, E773) apply to all models covered here.

When should I call a technician instead of DIYing a Navien repair?

Call a licensed plumber or HVAC technician if the error involves gas valve replacement, PCB (control board) diagnosis, internal heat exchanger cleaning, or if the error returns within 24 hours after repair. Gas component work should always be verified by a professional with proper leak detection equipment.

Related Navien Waterheater Error Codes

Code: E110Navien E110 Error Code: Exhaust Blockage and Venting Fault Explained Code: E003Navien E003 Error Code: Ignition Failure Fix for NPE and NCB Series Code: NO-HOT-WATERNavien Tankless Water Heater: No Hot Water Troubleshooting Guide Code: E012Navien E012 Error Code: Flame Failure During Operation Code: RESETHow to Reset a Navien Tankless Water Heater and Clear Error Codes Code: E001Navien E001 Error Code: Ignition Failure (First Attempt)Code: E302Navien E302 Error Code: False Flame Detection Code: E762Navien E762 Error Code: High Temperature Limit Exceeded Code: E773Navien E773 Error Code: Exhaust Overheat Thermal Limit

Same Fix on Other Brands

Rinnai waterheaterRinnai Tankless Water Heater Error Codes

Models Known to Experience HUB Errors

This repair applies to most Navien waterheaters with this error code. Common model numbers include:

NPE-240A, NPE-180A, NPE-210A, NCB-240E, NPN-199A

Last verified for technical accuracy on March 14, 2026