Navien Error Codes List and Fixes (November 2026)

Navien tankless water heaters and combi boilers show E codes when something is wrong. Below are the most common codes, what they mean and what you can safely check. For anything involving gas, burners or circuit boards, call a licensed technician or Navien support (1-800-519-8794).

What Does Navien Error Codes Mean?

Navien error codes start with E followed by a number. Each code points to a part or condition, like ignition, flame, temperature sensors, venting or water flow.

Quick Fix for Navien Error Codes

1. Write down the exact code.
2. Turn the unit off and on once to reset.
3. Check gas supply, water valves and venting.
4. If the code returns, call a technician.

Common Causes

• Gas supply problems
• Blocked air intake or exhaust vent
• Scale buildup in hard water
• Faulty sensors
• Water flow problems

How to Fix Navien Error Codes Step by Step

1. E003: ignition failure

Check that the gas valve is open and other gas appliances work. Reset once. If it returns, call a technician.

2. E012: flame loss

Flame went out during operation. Often gas pressure or venting. Call a technician if it repeats.

3. E016: heat exchanger overheating

Often scale buildup or low water flow. Flush/descale the unit and clean the inlet filter.

4. E030: exhaust overheating

Check that the vent is not blocked. Needs a technician if it continues.

5. E110: air pressure or exhaust blockage

Check intake and exhaust pipes for blockage, snow or nests.

6. E407: hot water outlet sensor fault

The outlet thermistor may be faulty. Technician repair.

7. E439: flow sensor fault

See our Navien E439 guide.

8. E515: circuit board (PCB) error

Reset once. If it returns, the PCB may need service.

Safety note

Turn off power and gas before inspecting. Never open sealed gas parts yourself.

FAQ

Where is the full code list?

In your unit installation or user manual, in the troubleshooting section.

How often should I flush my Navien?

Once a year, or more often with hard water.

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