Understanding Error Codes - Navien NPN-160U User's Information Manual

5.2 Understanding Error Codes

When an error code appears on the front panel, refer to the following chart for a definition and possible remedy
for the situation.
Error Code Reason
E003 Ignition failure
E004 False flame detection
E012 Flame loss
E016 Overheating of heat exchanger
E046 Abnormal operation: limit control
E056 Abnormal operation: Modulating gas valve
E109 Abnormal operation: fan motor
E110 Abnormal air pressure
Abnormal operation : Air volume Open/
E127
Short/Default value/No answer
E157 Abnormal operation : Air volume control
E170 Antifreeze heater Open/Short
Hot water outlet: thermistor open or short
E407
circuit
Cold water inlet1: thermistor open or short
E421
circuit
E434 Abnormal operation: water adjustment valve
E438 Abnormal operation: circulation pump
E439 Abnormal operation: flow sensor
Hot water inlet2: thermistor open or short
E441
circuit
E445 Abnormal operation: Bypass mixing valve
E515 Abnormal operation: PCB
22 Troubleshooting
Self-diagnostic / Action
Ensure that the main gas supply valve is open.
Ensure that the gas manifold and the fuel DIP
SW setting match the supplied gas type.
Ensure that the electrical cord is properly
grounded.
Clean the intake air filter. See page 19.
Ensure that the electrical cord is properly
grounded.
Ensure that the gas manifold and the fuel DIP
SW setting match the supplied gas type.
Turn off the system for at least 30 minutes, and
then restart it.
Clean the cold water inlet filter. See page 19.
Flush the heat exchanger. See page 17.
Contact Technical Support at 1-800-519-8794.
Contact Technical Support at 1-800-519-8794.
Contact Technical Support at 1-800-519-8794.
Ensure that the vent pipe is free of obstructions.
Contact Technical Support at 1-800-519-8794.
Contact Technical Support at 1-800-519-8794.
Contact Technical Support at 1-800-519-8794.
Contact Technical Support at 1-800-519-8794.
Contact Technical Support at 1-800-519-8794.
Contact Technical Support at 1-800-519-8794.
External: Ensure that all water supply and return
lines are open.
Contact Technical Support at 1-800-519-8794.
Contact Technical Support at 1-800-519-8794.
Contact Technical Support at 1-800-519-8794.
Ensure that the electrical cord is properly
grounded.