Navien Tankless Error Code Troubleshooting

Like any other water heater, sometimes you may experience a problem with your Navien tankless water heater. When an issue arises, your Navien will likely display an error code on the LCD display on the front of the unit.

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There are a large number of unique Navien error codes that help with troubleshooting the issue. Some problems can be solved with simply resetting the water heater unit (press the Reset button on the front panel) but other require more work.

Below you’ll find the most common error codes for a Navien tankless water heater along with a suggested fix. Often, you can complete simple fixes on your own with a few tools but for some more complex problems, you’ll need to contact a professional plumber who is familiar with Navien models or go straight to the manufacturer for support.

Have a different tankless water heater brand that needs troubleshooting?

Navien Tankless Water Heater Error Codes

Error Code E003
What it Means: Ignition failure in your tankless water heater.

How to Fix: Confirm the main gas supply valve is open.

Error Code E004
What it Means: False flame detection.

How to Fix: Confirm properly grounded electrical cord.

Error Code E012
What it Means: Flame loss.

How to Fix: Confirm properly grounded electrical cord. Inspect and clean intake air filter.

Error Code E016
What it Means: Overheated heat exchanger.

How to Fix: Turn off the water heater for 30 minutes and restart. Inspect and clean the filter in cold water inlet. Flush the heat exchanger.

Error Code E030
What it Means: Exhaust overheating. The unit will shut down when the temperature in the flue exceeds 149° Fahrenheit (65° Celcius).

How to Fix: Turn off the water heater for 30 minutes and restart. Inspect and clean the filter in cold water inlet. Flush the heat exchanger.

Error Code E046
What it Means: Abnormality in limit control.

How to Fix: Call technical support (800-519-8794).

Error Code E047
What it Means: Abnormality in exhaust thermostat.

How to Fix: Call technical support (800-519-8794).

Error Code E060
What it Means: Abnormality in dual venturi.

How to Fix: Call technical support (800-519-8794).

Error Code E109
What it Means: Abnormality in fan motor.

How to Fix: Inspect and clean the intake air filter.

Error Code E110
What it Means: Abnormality in air pressure.

How to Fix: Confirm there are no obstructions in the exhaust pipe. Inspect and clean intake air filter.

Error Code E407
What it Means: Thermistor open or short circuited (hot water outlet).

How to Fix: Call technical support (800-519-8794).

Error Code E421
What it Means: Thermistor open or short circuited (cold water inlet 1).

How to Fix: Call technical support (800-519-8794).

Error Code E432
What it Means: Thermistor open or short circuited (cold water inlet 2).

How to Fix: Call technical support (800-519-8794).

Error Code E434
What it Means: Abnormality in water adjustment valve.

How to Fix: Call technical support (800-519-8794).

Error Code E438
What it Means: Abnormality in circulation pump.

How to Fix: Confirm all water supply and return lines are open. Check direction of the internal 2-way valve.

Error Code E439
What it Means: Abnormality in flow sensor.

How to Fix: Call technical support (800-519-8794).

Error Code E441
What it Means: Thermistor open or short circuited (hot water inlet 2).

How to Fix: Call technical support (800-519-8794).

Error Code E445
What it Means: Abnormality in bypass mixing valve.

How to Fix: Call technical support (800-519-8794).

Error Code E515
What it Means: Abnormality in PCB.

How to Fix: Confirm proper grounding of electrical cord.

Error Code E517
What it Means: Abnormality in DIP switch setting.

How to Fix: Call technical support (800-519-8794).

Error Code E593
What it Means: Abnormality in front panel key.

How to Fix: Call technical support (800-519-8794).

Error Code E615
What it Means: Abnormality in input and memory.

How to Fix: Call technical support (800-519-8794).

Error Code E736
What it Means: Abnormality in cascade communication.

How to Fix: Call technical support (800-519-8794).

Error Code E740
What it Means: Abnormality in outdoor temperature sensor.

How to Fix: Call technical support (800-519-8794).

Error Code E760
What it Means: Flushing/service alarm.

How to Fix: Call technical support (800-519-8794).

Error Code E782
What it Means: Abnormality in main panel communication.

How to Fix: Call technical support (800-519-8794).

Error Code E785
What it Means: Abnormality in flow switch/sensor.

How to Fix: Call technical support (800-519-8794).

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4 thoughts on “Navien Tankless Error Code Troubleshooting”

  1. Since I’ve had it for a year and a half every so often no hot water will come out of the Faucets until I go outside to the heater and push the reset button and then it comes back on. I’ve had to do this on both models. The LP180s and the 240 models.

  2. Have Model NR-240 LP since 2012. Unit has gone into error 026 while I shaving (no other fixtures using ANY water and no other appliances using gas)! Has happened while people are showering. Happens when washing dishes in the sink. Every time = Error Code 026. Navien Tech Support suggested multiple causes: ‘insufficient gas supply’ (either not enough propane in supply tank or inadequate gas supply from the gas regulator), ‘water pressure insufficient’ to ‘inadequate air intake supply’. Had gas company on site and had Navien Tech on phone with him. All potential ’causes’ were dispelled… LP tank is never less than half full, water supply/pressure consistently adequate and stable, air intake is provided in a 1,200 plus cubic foot externally vented storage area… and using manometer (spelling?) gas company verified that the gas supply/pressure/flow was exactly as required by manufacturer. I even had the gas company install a gas regulator specificall for the Navien unit (separating it from my gas fireplace) but the problem persisted. I was keeping a log of the problem, but stopped out of frustration. Mostly because I was told, ‘Call when it happens.’ I did call a few times and read off the error code (was told to power off/on and did it – which is certainly not a resolution), another time Tech had me open the unit and read off an internal LED panel code (was then told to power off/on – again, not a resolution), another time was directed to change a few ‘dip’ switches… and finally, power the unit off and on (if this sound repetitious — it is!).
    I am awaiting the catastrophic failure of the heater and will replace it with a Rinnai. I have shared my story with every other homeowner as they are building their house (and have posted it on our housing development web page). I have a close friend on an Architectural Review Board for a housing development (6,000 plus home sites) and he recommends reading my “review” of the product to every person that is beginning to build. You can not even write to the Navien management to ask for assistance… there is no web site link for it.
    Completely disappointed in the performance of the device as well as the ‘support’ team behind it.

    • Wow, I’m sorry for your experience. I’ve only heard about error code 026 one other time (Navien has no information about it online or in their manuals as far as I know). If I recall correctly, their issue was electrical because their home was susceptible to power flickers and short outages from time to time. Not sure if it was resolved or if your issue is even similar.

  3. I have a navien 240a. Same issue. Every 1-2 months unit will not fire error code 003. Hit the reset switch and everything is fine. Not acceptable

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