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Navien Tankless Water Heater Error Codes

Updated
We cracked the mystery behind the error codes showing on your Navien tankless water heater.

Have you encountered a problem with your Navien tankless water heater? Is it displaying an error code but you don’t know what it means?

Although tankless water heaters don’t require much maintenance, they aren’t perfect and problems do occur, leaving you with no hot water. Navien is a manufacturer that provides an error code to help you, but this isn’t very useful if you don’t know what each code means.

To help you solve the problem, we have provided a breakdown of various Navien error codes in this article. We will also take a more in-depth look at some of the most common Navien tankless water heater problems.


Navien Tankless Error Codes Breakdown

Tankless water heater systems require several essential parts to work properly, so you are bound to encounter problems at some point. Each error code your tankless heater might display corresponds to a specific issue with the boiler, so read on for a comprehensive list. It should explain most Navien tankless water heater error codes and speed up your troubleshooting.

Error Code E003

What It’s Telling You

  • There is an ignition failure.

The Solution

  1. Make sure the main gas valve is completely open and there is no abnormal gas connection.

Error Code E004

What It’s Telling You

  • False flame detection.

The Solution

  1. Confirm that the main electrical cord is properly grounded.

Error Code E012

What It’s Telling You

  • There has been a flame loss.

The Solution

  1. Clean the intake filter: Remove the filter and clean it with a toothbrush under running water. Ensure the power is off before you remove the filter. Let it dry before placing it back into the unit.
  2. Check the connections: Confirm that the electrical cord is properly grounded.

Error Code E016

What It’s Telling You

  • The heat exchanger is overheating.

The Solution

  1. Restart the unit: Turn it off completely for at least 30 minutes, then restart it.
  2. Clean the inlet filter: Remove the inlet filter and clean it under running water with a toothbrush.
  3. Flush the heat exchanger: While the cold water inlet filter is out, flush the heat exchanger. Refer to your owner’s manual for specific instructions.

Error Code E030

What It’s Telling You

  • The exhaust is overheating: The unit shuts down automatically when the flue pipe exceeds a temperature of 149 degrees Fahrenheit.

The Solution

  1. Restart the unit: Turn the system off for at least 30 minutes before restarting it.
  2. Wash the inlet water filter: Remove the inlet water filter and clean it under running water with a toothbrush.
  3. Flush the heat exchanger: Consult your owner’s manual for specific instructions.

Error Code E046

What It’s Telling You

  • Unusual operation: Limit control.

The Solution

  1. Call Navien technical support at 1-800-519-8794.

Error Code E047

What It’s Telling You

  • Unusual operation: Exhaust thermostat.

The Solution

  1. Call Navien technical support at 1-800-519-8794.

Error Code E060

What It’s Telling You

  • Unusual operation: Dual venturi.

The Solution

  1. Call Navien technical support at 1-800-519-8794.

Error Code E109

What It’s Telling You

  • Unusual operation: Fan motor.

The Solution

  1. Rinse out the air intake filter: Remove the air intake filter and wash it under running water. Scrub it with a toothbrush. Let it dry and place it back into the unit.

Error Code E110

What It’s Telling You

  • Unusual air pressure.

The Solution

  1. Clear blockages: Ensure there are no obstructions in the exhaust pipe.
  2. Wash the air intake filter: Remove the air intake filter from the unit and wash it under running water. Scrub it with a toothbrush. Let it dry before placing it back.

Error Code E407

What It’s Telling You

  • An issue with the hot water outlet: This could be either an open thermistor or a short circuit.

The Solution

  1. Call Navien technical support at 1-800-519-8794.

Error Code E421

What It’s Telling You

  • A problem with the first cold water outlet: An open thermistor or a short circuit.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E432

What It’s Telling You

  • An issue with the second cold water outlet: An open thermistor or a short circuit

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E434

What It’s Telling You

  • Unusual operation: Water adjustment valve.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E438

What It’s Telling You

  • Unusual operation: Circulation pump.

The Solution

  1. External: Check that all the water return and supply lines are free and open.
  2. Internal: Check the direction of the two-way valve.

Error Code E439

What It’s Telling You

  • Unusual operation: Flow sensor.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E441

What It’s Telling You

  • An issue with the second hot water inlet: An open thermistor or a short circuit.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E445

What It’s Telling You

  • Unusual operation: Bypass mixing valve.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E515

What It’s Telling You

  • Unusual operation: Abnormal PCB behavior.

The Solution

  1. Ensure that the main electrical cord is properly grounded.

Error Code E517

What It’s Telling You

  • Unusual operation: DIP switch setting.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E593

What It’s Telling You

  • Unusual operation: Front panel key.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E615

What It’s Telling You

  • Unusual operation: Memory and input.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E736

What It’s Telling You

  • Unusual operation: Problem with internal communication.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E740

What It’s Telling You

  • Unusual operation: Outdoor temperature sensor.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E760

What It’s Telling You

  • Maintenance alarm: Flushing or service required.

The Solution

  1. Contact a local professional to perform a boiler service.

Error Code E782

What It’s Telling You

  • Unusual performance: Issue with the main panel communication.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Error Code E785

What It’s Telling You

  • Unusual performance: Issue with the flow switch/sensor.

The Solution

  1. Call Navien’s technical support at 1-800-519-8794.

Common Navien Tankless Water Heater Problems

Navien’s tankless water heaters are among the best available today, but this wasn’t always the case. Some of their pre-2011 models suffered from unfortunate issues (1). In fact, some models were even recalled (2).

Thankfully, Navien stepped up its game and issues are now far less frequent. The company was one of the first to offer tankless condensing water heaters for residential use. Problems are bound to occur when you are at the forefront of new technology, and this was the case with Navien.

If you have a pre-2011 model, here are some key issues you should look out for — or might have already experienced.

Turn The Power Off

Before doing anything else with your unit, make sure the power is off. Although it is a gas-powered boiler, it still uses electricity. To stay safe while working on your boiler, switch the breaker to the “Off” position.

1. Motherboard and Control Board Failure

A common issue involves the motherboard, control board, or sometimes both. These are the “brains” of the tankless unit, receiving and transferring information. Unfortunately, when these fail, it could mean that there’s a larger flaw with the boiler.

On Navien’s pre-2011 models, this seems to happen quite frequently. The symptoms are relatively easy to spot. Your unit will likely turn on and off repeatedly.

If it doesn’t switch on and off, check the display for error code E003 — the code for ignition failure. The simplest way to fix this is by unplugging the unit, waiting a while, and then reconnecting it.

If this doesn’t fix the issue, the control board will likely need replacing. Contact your installer for assistance.

2. Flow Sensor Corrosion

One of the most common issues with the company’s earlier models affected the flow sensors. They were made from a material that was prone to corrosion.

A flow sensor is an important part of any tankless water heater. Its main job is to detect an incoming flow of water and then activate the unit.

As Navien’s flow sensors corroded prematurely, they caused the units to shut down. A buildup of corrosion would inhibit the boiler’s operation, which could lead to other issues.

There’s one quick and easy fix to this issue but it’s only temporary. You need to turn the unit off, locate the flow sensor, gently pull it out and then blow on it. Then, place it back into the unit and turn on the power.

Navien provided a more permanent solution to this problem by improving the flow sensor material. Navien now uses stainless steel, which is resistant to rust and corrosion. If you have an older unit, you might be able to replace the part with a new one.

If this isn’t an option for you, purchase a 5-micron filter and install it by the water inlet valve.

3. Heat Exchanger Cracking

Fortunately, this problem isn’t as common as the previous two. However, it is still an issue you should be aware of.

If the heat exchanger begins to crack, it means there is a breach and harmful exhaust gasses could leak into your home. An immediate replacement is needed and there are no quick fixes to this problem. Contact Navien, as the heat exchanger should be under warranty.

How to Reset a Navien Tankless Water Heater

If there is an issue with your unit but it doesn’t display an error code, you can try resetting it. This is very easy and doesn’t require you to physically open up your heater.

Navien has made its units very user-friendly by adding a reset button on the front control panel. It is usually in the bottom corner opposite the “On/Off” button. To reset your unit, simply press the reset button and it should soon be ready to go (3).

If you have tried this and none of the listed error codes apply, contact an authorized technician.

Where is the Serial Number on a Navien Water Heater?

It is very important to know the serial number of your water heater, especially if you need to contact the manufacturer.

Finding the label with the serial number shouldn’t take long. It is usually on either the front door or the side.

Look at the side of your unit. There should be a large yellow label that contains the energy guide and any warnings. The serial number should be nearby.

Don’t worry if it isn’t on the side, as the exact location depends on the specific unit. It is often on the outside but with other units, you might need to open the unit’s door.

FAQs

How Do You Troubleshoot a Navien Water Heater?

There shouldn’t be too much guesswork involved when troubleshooting a Navien water heater, as long as the unit is still receiving electricity. The unit’s front panel should display an error code when an issue occurs, which corresponds to a specific problem with your boiler. Look for the error code in our list and you should be able to determine the issue.

Where Is the Reset Button on a Navien Tankless Water Heater?

The reset button of a Navien tankless water heater is usually located on the control panel, in the bottom corner opposite the “On/Off” switch. This means you won’t need to physically open up your heater unit, so resetting the heater should be one of your first troubleshooting tactics before you advance to more complicated methods.

How Long Do Navien Tankless Water Heaters Last?

Tankless water heaters usually have a considerably longer lifespan than their tank counterparts. This is because tanks are subjected to more corrosion, which eventually causes holes and leaks. As tankless water heaters are in contact with water for a much shorter period, they should last 15 to 20 years and perhaps longer with proper maintenance.


Error Code: Out of Time

Tankless water heaters are advanced machines capable of providing an indefinite supply of hot water for your needs. However, they aren’t flawless and issues do occur. Thankfully, Navien included error codes to help you determine the specific problem.

By checking the error code, you will be able to give customer support or a professional technician a clearer picture of the problem you are currently dealing with. You might even be able to resolve the issue yourself if you know how to fix it, which could save you some money.

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About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.