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.

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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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