Navien NPN-160U User's Information Manual page 23

Error Code Reason
E517 Abnormal operation: DIP switch setting
E593 Abnormal operation: front panel key
E594 Abnormal operation: EEPROM
E615 Abnormal operation: input and memory
Abnormal operation: cascade
E736
communication
Abnormal operation: outdoor temperature
E740
sensor
E760 Flushing/service alarm
E762 Vent pipe not properly inserted
E773 Abnormal operation: gas connection
Abnormal operation: main panel
E782
communication
E785 Abnormal operation: flow switch/sensor
E786 Abnormal operation: panel connection
If any of these remedies do not resolve the problem, contact Technical Support at 1-800-519-8794.
Self-diagnostic / Action
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.
Contact the installer to perform routine service.
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.
Troubleshooting 23