All tankless water heaters will surprise you with an unexpected error code eventually. Unfortunately, it’s always at an inopportune time. The same holds true for Navien tankless water heaters.
While it is unpleasant, the error code can help you diagnose the problem and allow you to take corrective action.
Read More: navien error code 003 how to fix
When an error code occurs, you’ll likely hear an audible “beeping” alarm. If you have no hot water, you may have overwhelmed your tankless water heater’s capacity or have at least one error code.
This guide will discuss and go over the Navien tankless water heater error codes, their meaning, troubleshooting, and more. So let’s take a look.
Error Code E001: Heat Exchanger Overheating
Navien error code E001 is caused by an overheating heat exchanger. To fix Navien error code E001, you may need to clean the strainer and flush the heat exchanger. You must ensure that the flow rate and voltage of the PCB at the pump meet specifications and that water circulates correctly.
This guide will show you how to maintain your tankless water heater. In Easy Maintenance Tips for Tankless Water Heaters w/Photos will outline how to perform tankless water heater flushing and other maintenance.
Error Code E002: Low Pressure on the Heating Side
Navien error code E002 means there is low pressure on the heating side. Navien Low water pressure could cause error code E002 so make sure the unit gets enough water. To fix the error code, you may need to restart your unit.
Error Code E003: Ignition Failure
Navien error code E003 indicates a failure in the ignition of the unit. If your Navien is displaying an error code E003, ensure the gas supply is on and working, that the unit is powered, the ground wire is connected, and that the igniter is producing a spark.
If required, replace or clean the igniter electrode.
It can also happen due to a power outage. You may want to consider a battery backup power supply for the tankless water heater if you live in an area where there are frequent blackouts and power outages.
Error Code E004: False Flame Detection
Navien error code E004 is an indication that the unit is detecting a false flame. To troubleshoot Navien error code E004, confirm that the ground wire is connected correctly and is not loose. Check if the igniter produces a spark.
Error Code E011: High Pressure on Heating Side
Navien error code E011 means there is high pressure on the heating side. This error code can be corrected by turning off the unit, draining any water, then switching it on again. If the error persists check the condition the sensor. If the sensor is damaged or worn, replace it.
Error Code E012: Flame Loss
Navien error code E012 means there is a flame loss. To troubleshoot and fix Navien error code E012, confirm that the main gas valve is open and the gas pressure is within spec. You should also check the intake air filter and ground wire. Also, make sure the power supply is working properly.
In some cases, you may need to adjust the anti-short cycling timing.
Error Code E016: Heat Exchanger Overheating
Navien error code E016 means the heat exchanger is overheating. To fix and troubleshoot Navien error code E016, switch the unit off for 30 seconds and then back on. Clean the cold water filter, strainer and heat exchanger. Verify the 3-way valve, high limit switch and PCB.
Error Code E030: Abnormal Exhaust Temperature
Navien error code E030 is caused by an overheating exhaust. To troubleshoot and fix Navien error code E030, switch the unit off for 30 seconds and then power it back on. The heat exchanger and strainer should be checked. If necessary, clean the strainer and flush out the heat exchanger.
The unit will cease working if the exhaust temperature exceeds 230°F (110 °C) for more than 10 seconds.
Error Code E046: Heat Exchanger Error
Navien error code E046 means that there is a short at the heat exchanger thermistor. To fix Navien error code E046, check the condition of the wiring at the heat exchanger thermistor. Make sure there are no loose connections.
Navien E046 may also indicate a limit controller. It is best to call a licensed contractor if you have any questions.
Error Code E047: Exhaust Thermistor Error
Navien error code E047 is an indication of a problem in the operation of the exhaust thermistor. Navien E047 error can be caused by an improperly connected or shorted exhaust thermostator. To fix this error code you will need to inspect the wiring and connection to the exhaust thermistor.
Error Code E060: Dual Venturi Limit Switch Error
Navien error code E060 means a problem with the dual venturi limit switch. If your Navien displays an error code E060, you need to check the dual venturi connection. The dual venturi connection may have to be replaced completely in some cases.
Error Code E109: Fan Motor Activity Error
Navien error code E109 indicates an error with the fan motor. To troubleshoot Navien error code E109, check and clean, if necessary, the air intake filter and the fan motor. If the error code persists, measure the PCB’s voltage and replace the fan if the voltage is within spec.
Error Code E110: Exhaust Blockage
Navien error code E110 means there is an exhaust blockage. To fix the Navien error code, E110 ensures nothing obstructs or blocks the exhaust pipe and that the exhaust pipe is clear. Also, check the condition of your intake air filter. If necessary, clean it.
Condensate blockage can also cause this error code. The air pressure sensor may need replacement if the error code does not disappear after reset.
Error Code E127: APS Error (Open, Short, Initial Value or No Response)
Navien error code E127 is indicative of a problem with the air pressure sensor (APS). Error An open or shorted air pressure sensor (APS) can cause code E127. It is possible to turn it off and examine the APS. If the error code persists, it is possible to replace the APS.
Error Code E205: H/E Outlet Error: Thermistor Open or Short
Navien error code E205 indicates a problem with the operation of the heating supply thermistor. An open or shorted thermistor can cause the Navien error code E205. To fix this error code, inspect the heating supply thermistor’s condition and the pump wiring connectors.
Error Code E218: H/E Inlet Error: Thermistor Open or Short
Navien error code E218 means there is a problem with the operation of the heating return thermistor. An open or short thermistor can cause the Navien error code E218. To fix this error code, inspect the heating return thermistor’s condition and the pump wiring connectors.
Error Code E302: Low Water Pressure Error
Navien error code E302 means that the water pressure is too low. If your Navien is displaying an error code E302, check the water feeder valve and the water pressure and the water pressure relief valve. Repair any broken parts as needed.
Error Code E352: High Water Pressure Error
Navien error code E352 is indicative of high water pressure. If your Navien displays an error code E352, you need to check the water pressure is within good rangers and check the activity of the feeder valve and the water pressure relief valve.
Error Code E353: Water Pressure Sensor Error
Navien error code E353 indicates a problem with the water pressure sensor. An open or shorted sensor can cause Navien error code E353. Verify that the wiring and water pressure sensor are in good condition. If necessary, replace the sensor.
Error Code E407: Hot Water Outlet 1: Thermistor Open or Short
Navien error code E407 is a sign of a problem with the hot water outlet thermistor. An open or shorted sensor causes the Navien error code E407. To fix it, check the thermistor’s condition and wiring. Replace the thermistor if necessary.
Error Code E421: Cold Water Inlet 1: Thermistor Open or Short
Navien error code E421 means there is a problem with the cold water inlet 1 thermistor. An open or shorted sensor causes the Navien error code E421. To fix it, check the thermistor’s condition and wiring. If needed, replace the cold-water inlet thermistor.
Error Code E432: Cold Water Inlet 2: Thermistor Open or Short
Navien error code E432 is a sign of a problem with the cold water inlet 2 thermistor. An open or shorted sensor causes the Navien error code E432. To fix it, check the thermistor’s condition and wiring. Replace the thermistor if necessary.
Error Code E434: Abnormality in Water Adjustment Valve
Navien error code E434 means there is a problem with the water adjustment valve. The Navien error code E434 can be caused by an open or shorter water adjustment valve. Check the condition and wiring of your tankless water heater by turning it off. Call for service if needed.
Error Code E438: Abnormality in Circulation Pump
Navien error code E438 means there is a problem with the circulation pump. This error code can be fixed by checking the water supply, circulators, flow sensor and pump. If you receive error code E438, it is possible to replace the pump or flow sensor.
Error Code E439: Abnormal Flow Sensor
Navien error code E439 is indicative of a problem with the flow sensor. Error code E439 can be caused by a faulty flow sensor, PCB, or no cold water supply.
This error code can be fixed by checking if water is flowing while the cascade system has been switched off. Check the condition of your flow sensor connector if there is water flow.
Error Code E441: Hot Water Outlet 2: Thermistor Open or Short
Navien error code E441 is a sign of a problem with the hot water outlet 2 thermistor. An open or shorted sensor causes the Navien error code E441. To fix it, check the thermistor’s condition and wiring. Replace the thermistor if necessary.
Error Code E445: Abnormal Mixing Valve
Navien error code E445 indicates an abnormality in the mixing valve. The Navien error code E445 is typically caused by a faulty feedback sensor, damaged, opened, shorted, or blocked mixing valve, or a defective PCB. Call a licensed technician if you have any questions.
Error Code E480: External Tank Thermistor Open or Short (System Boiler Thermistor Setting Only)
Navien error code E480 means there is a problem with the external tank thermistor, typically caused by an open (at temperatures below 14°F) or shorted sensor. Check the sensor’s connectors to ensure they are installed correctly and are not wet. Replace the tank thermostat if necessary.
Error Code E515: PCB Error
Navien error code E515 indicates an issue with the PCB. In the case of an error code E515, the PCB, PCB’s monitoring device, igniter, fan, dual venturi, and the 3-way valve should all be inspected. They should be in good condition and securely connected to the PCB.
Error Code E517: DIP Switch Setting Error
Navien error code E517 signifies a problem with the dip switch. To troubleshoot and fix Navien error code E517, you need to check the dip switches on the unit’s front panel and the PCB. If the error persists but everything seems normal, you should call a licensed technician.
Error Code E593: Abnormal Panel Key
Navien error code E593 is caused by a problem with the operation of the front panel keys. To fix the Navien error code E593, you need to inspect if the panel keys operate as they should. If they do restart the unit and if they don’t replace the front panel.
Error Code E594: Partial PCB Communication Error
Navien error code E594 indicates a partial PCB communication error or an EEPROM error. Check the unit’s PCB for any damage or wiring issues. If the error persists and nothing looks out of the ordinary, contact a licensed contractor to evaluate the condition of your Navien tankless water heater.
To ensure that your tankless water heater is in top condition, you will also need to inspect the condition of the wires and wiring for the flame rod and exhaust sensor.
Error Code E615: Input and Memory Error
Navien error code E615 can indicate an input data error or a memory error. Reset the unit. Check the condition and wiring of the flame rod, exhaust sensor, and pressure sensor. Measure the pressure sensor’s output voltage and ensure it is within range. Contact us if you need assistance.
Error Code E736: Abnormal Cascade Communication
Navien error code E736 indicates a problem with the cascade communication. Check that the PCB version you are using is compatible. Make sure to check the readylink cascade cable installation and cascade settings. If the problem persists, contact a licensed technician.
Error Code E740: Outdoor Sensor Error
Navien error code E740 means there is a problem with the outdoor temperature sensor. An open or shorted sensor can cause Navien error code E740. To fix it, ensure that the sensor’s wiring is in good condition and working correctly and that the outdoor reset curve is dialed in properly.
See our article Can Water Heaters Be Installed Outside: What You Should Know for more information on outdoor tankless water heater models.
Error Code: E760: Flushing Alarm
Navien error code E760 is a flushing service alarm. This is not an error code, but a reminder. If your Navien tankless water heater displays an error E760, this means that you need to flush the heat exchanger.
Here is a guide to tankless water heater maintenance. In Easy Maintenance Tips for Tankless Water Heaters w/Photos will outline how to perform tankless water heater flushing and other maintenance.
Error Code E782: Main Panel Communication Error
Navien error code E782 indicates a communication error within the main panel. To troubleshoot the Navien error code E782, inspect the condition and operation of the PCB. To fix this error, you may need to have a licensed contractor assess your unit’s condition and replace the PCB if necessary.
Error Code E783: OT-remote Controller Error
Navien error code E783 means there is a problem with the operation of the OT-remote controller. Examine the condition and replace the controller if necessary.
Error Code E785: Abnormal Flow Switch Operation
Navien error code E785 means there is a problem with the operation of the external flow switch. The condition of the flow sensor and cold water line should be checked. Check if the flow switch is in the off or on position and the thermal block’s resistance. Replace the controller or sensor if necessary.
Error Code E787: Device Reset Error
Navien error code E787 indicates that there has been a problem while the unit has been reset. After confirming that the unit is functioning properly, please turn off the device for at least 30 seconds. If the error code persists, have a technician evaluate the unit’s condition.
Tankless water heaters last 20 years on average and during that time you’re sure to have at least one of these Navien error codes. This guide will be very helpful when you are looking for a tankless water heater. We hope that you bookmark this page to make it easier in the future.
Other Troubleshooting Tankless Water Heater Error Code Guides
- Troubleshooting Tankless Water Heater Error Codes: Rinnai
- Troubleshooting Tankless Water Heater Error Codes: Rheem
- Troubleshooting Tankless Water Heater Error Codes: Noritz
- Troubleshooting Tankless Water Heater Error Codes: Bosch
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