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Navien Error Codes & Diagnostic Codes

Updated · by Aurora Star Tech Inc.

Navien error codes and diagnostic codes: look up a code to see what it means, the likely causes and the steps to fix it.

Navien error codes by equipment type

Navien Boiler error codes

CodeMeaning
E001Heat exchanger overheat
E003Ignition failure
E004False flame detected
E012Flame loss
E016Heat exchanger overheat (check flow / system filters)
E030Exhaust overheat
E031Burner overheat
E046Heat exchanger thermistor fault
E047Exhaust thermistor fault
E060Dual venturi fault
E109Fan motor fault
E110Exhaust blockage
E205Heating supply temperature sensor
E218Heating return temperature sensor
E278External system supply sensor not detected
E279External system return sensor not detected
E291Return temperature higher than supply
E302Low water pressure
E352High water pressure
E353Water pressure sensor fault
E480DHW tank sensor not detected
E515PCB fault
E517DIP switch setting fault
E594EEPROM fault
E615Memory fault
E736Cascade communication fault
E740Outdoor sensor not detected
E762Vent pipe not fully inserted (VID)
E777Low water cutoff activated
E782Front panel communication fault
E784Zone controller communication fault
E786Improper front panel detected
E788Incorrect gas type setting

Navien Combi Boiler error codes

CodeMeaning
E001Heat exchanger overheat
E003Ignition failure
E004False flame detected
E012Flame loss
E016Heat exchanger overheat (overheating of heat exchanger)
E030Exhaust overheat (abnormal exhaust temperature)
E031Burner overheat
E046Heat exchanger thermistor / overheat sensor fault
E047Exhaust thermistor fault
E060Dual venturi fault
E109Fan motor fault
E110Exhaust blockage / abnormal air pressure (APS)
E205Heating supply temperature sensor fault
E218Heating return temperature sensor fault
E278External (system) supply sensor not detected
E279External (system) return sensor not detected
E302Low water pressure (internal LWCO)
E351Auto feeder (make-up water) valve fault
E352High water pressure
E353Water pressure sensor fault
E407DHW outlet temperature sensor fault
E421DHW cold water inlet sensor fault
E434Water adjustment (flow control) valve fault
E439No DHW flow detected / flow sensor fault
E441DHW outlet 2 sensor fault
E445Mixing (bypass) valve fault
E515PCB fault
E517DIP switch setting fault
E594EEPROM fault
E615Memory fault (input and memory)
E736Cascade communication fault
E740Outdoor sensor not detected
E761Pump aquastat (pre-heat aquastat) not detected
E762Vent pipe not fully inserted (VID)
E773Improper gas type detected
E777Low water cutoff (LWCO) activated
E782Front panel communication fault
E784Zone controller communication fault
E786Improper front panel
E788Incorrect gas type setting

Navien Tankless Water Heater error codes

CodeMeaning
E003Ignition failure
E004False flame detection
E012Flame loss
E016Heat exchanger overheating
E030Exhaust overheating
E031Burner overheating
E046Limit control abnormal
E047Exhaust thermistor open or shorted
E060Dual venturi abnormal
E21No hot water
E109Fan motor abnormal
E110Abnormal air pressure
E407Hot water outlet thermistor open or shorted
E421Cold water inlet 1 thermistor open or shorted
E432Cold water inlet 2 thermistor open or shorted
E434Water adjustment valve abnormal
E438Circulation pump abnormal (with air handler)
E439Flow sensor abnormal
E441Hot water inlet 2 thermistor open or shorted
E445Bypass mixing valve abnormal
E515PCB abnormal
E517DIP switch setting abnormal
E593Front panel key abnormal
E594EEPROM abnormal
E615Input and memory abnormal
E736Cascade communication abnormal
E740Outdoor temperature sensor abnormal (with air handler)
E760Flushing / service alarm
E762Vent pipe not properly inserted
E773Wrong gas type detected
E782Main / panel communication abnormal
E785Flow switch / sensor abnormal (with air handler)
E788Gas type mismatch: DIP switch vs panel setting

Find codes by Navien model

Navien NCB-H

NCB-190/060HNCB-190/080HNCB-240/110HNCB-240/130HNCB-250/150H

Navien NFB-H

NFB-175HNFB-200H

Navien NFC-H

NFC-250/175HNFC-250/200H

Navien NHB-H

NHB-055HNHB-080HNHB-110HNHB-150H

Navien NPE-2

NPE-150S2NPE-180A2NPE-180S2NPE-210A2NPE-210S2NPE-240A2NPE-240S2

Navien NPN

NPN-120ENPN-160ENPN-160UNPN-180ENPN-180UNPN-199ENPN-199U

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.

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