Understanding Error Codes - Navien NHB H Series Installation And Operation Manual

11.14 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
E001 Heat Exchanger Overheat
E003 Ignition Failure
E004 False Flame
E012 Flame Loss
E016 Heat Exchanger Overheat
E030 Exhaust Overheat
E046 Heat Exchanger Thermistor
E047 Exhaust Thermistor
E060 Abnormal Dual Venturi
E109 Abnormal Fan Motor
E110 Exhaust Blockage
E205 Heating Supply Temp.Sensor
E218 Heating Return Temp.Sensor
E278 Ext. Supply Sensor Not Detected
E279 Ext. Return Sensor Not Detected
E291 Return Temp. Exceeds Supply
E302 Low Water Pressure
E352 High Water Pressure
E353 Water Pressure Sensor
E480 DHW Tank Sensor Not Detected
E515 Abnormal PCB
E517 Abnormal DIP Switch
E594 Abnormal EEPROM
E615 Abnormal Memory
E736 Cascade Communication
E740 Outdoor Sensor Not Detected
E762 Vent Pipe Not Fully Inserted
E777 Low Water Cutoff Activated
E782 Front Panel Communication
E784 Zone Controller Communication
E786 Improper Front Panel Detected
E788 Incorrect Gas Type Setting
If any of these remedies do not resolve the problem, contact Technical Support at 1-800-519-8794.
Self-diagnostic/Action
Check for proper system flow.
Check gas supply valve and igniter.
Check electric ground.
Check gas, venting and condensate trap.
Check flow, clean system filters.
Check flow, clean system filters.
Check thermistor connector.
Check thermistor connector.
Check dual venturi.
Check fan and venting.
Check exhaust venting.
Check flow, thermistor connector.
Check thermistor connector.
Check sensor connections.
Check sensor connections.
Check for reversed piping.
Check water pressure.
Check water pressure.
Check WPS.
Check sensor connections.
Check PCB connections.
Check DIP switch settings.
Check the PCB.
Check PCB connections.
Check cascade cable.
Check sensor connections.
Insert pipe 2-3/4" (70 mm) into exhaust collar.
Check supply water.
Check panel connections.
Check wiring and settings.
Check for correct panel version.
Check DIP switch setting.
Operating the Boiler 119