5. Troubleshooting
5.1 Error Code List
Error Code
Function
Self-diagnostic/Action
E003
Ignition failure
1. Check to see if the main gas supply valve is
open.
2. Check that the power is “ON”.
3. Check the igniter for spark.
E004
False flame detection
1. Ensure ground wire is connected.
2. Check the igniter for spark.
E012
Flame loss
1. Check the main gas line (Is the valve open?).
2. Check intake air filter.
3. Check ground wire.
4. Check power supply.
E016
E030
1. Turn OFF the system for at least 30 minutes
then restart.
2. Clean the inlet water filter.
Overheating of heat exchanger
3. Check the water adjustment valve.
4. Check the heat exchanger; a flush may be
necessary.
1. Turn OFF the system for at least 30 minutes
Exhaust Overheat: exhaust limit switch then restart.
shuts down the unit when the flue
2. Clean the inlet water filter.
temperature exceeds 230 °F (110 °C)
3. Check the water adjustment valve.
for more than 10 minutes.
4. Check the heat exchanger; a flush may be
necessary.
E046
Abnormal heat exchanger thermistor
Check heat exchanger thermistor connection
E047
Abnormal exhaust thermistor
Check exhaust thermistor connection.
E060
Abnormal operation: dual venturi
Check the Dual Venturi connection.
E109
Abnormal fan motor activity
1. Check and clean the intake air filter.
2. Check and clean the fan motor.
E110
Exhaust blockage
1. Check the exhaust pipe for obstructions.
2. Check and clean the intake air filter
E407
Hot water outlet1: thermistor open or
short
E421
Cold water inlet1:thermistor open or
short.
E432
Cold water inlet2: thermistor open or
short.
1. Check the thermistor.
2. Replace the thermistor.
Error Code
Function
Self-diagnostic/Action
E434
Abnormal water adjustment valve.
Check the water adjustment valve.
E438
Abnormal circulation pump.
1. Check the circulation pump.
2. Check the flow sensor.
3. Check the cold water main line.
E439
Abnormal flow sensor
Check the flow sensor.
E441
Hot water inlet2: thermistor open or
short.
1. Check the thermistor.
2. Replace the thermistor.
E445
Abnormal bypass mixing valve.
Check the bypass mixing valve.
E515
Abnormal PCB
Check the PCB for damage or defects.
E517
Abnormal dip switch setting
Check the dip switches on the front panel
and PCB.
E593
Abnormal panel key
Check the Panel
E615
Abnormal input & memory
Check the PCB.
1. Check the Ready-Link cable.
E736
Abnormal cascade communication
E760
Flushing/service alarm
E782
Abnormal Main-Panel communication Check the PCB.
2. Check the cascade settings.
A heat exchanger flush is necessary.
If any of the above solutions do not resolve the problem with the Water Heater, contact Navien’s
Technical department at 1-800-519-8794.
There will be error codes displayed on the front panel and recorded on the PCB board (within the
unit) of any problems or failures that occur with the Water Heater.
IMPORTANT
To reset the Water Heater, either press the [Reset] button on the front panel or disconnect,
then reconnect electrical power to the water heater.