Brand guide
Navien Error Codes: Meanings & Safe Checks
Match the equipment family and displayed code before following any check.
The official NAA Air Conditioner Installation and Operation Manual identifies ATL as overtemperature protection.
The official NAA Air Conditioner Installation and Operation Manual identifies d0 as running indication during oil-return mode.
The official NAA Air Conditioner Installation and Operation Manual identifies dC as running indication during forced-cooling mode.
The official NAA Air Conditioner Installation and Operation Manual identifies F0 as communication failure (outdoor unit).
The official NAA Air Conditioner Installation and Operation Manual identifies F1 as low pressure switch error.
The official NAA Air Conditioner Installation and Operation Manual identifies F4 as t4 outdoor ambient temperature sensor error.
The official NAA Air Conditioner Installation and Operation Manual identifies F5 as t5 compressor discharge temperature sensor error.
The official NAA Air Conditioner Installation and Operation Manual identifies F6 as t3 condensing temperature sensor error.
The official NAA Air Conditioner Installation and Operation Manual identifies F7 as t7 temperature sensor error.
The official NAA Air Conditioner Installation and Operation Manual identifies F8 as t7 temperature sensor error in detecting condensate risks.
The official NAA Air Conditioner Installation and Operation Manual identifies F9 as ac overvoltage or undervoltage protection.
The official NAA Air Conditioner Installation and Operation Manual identifies FA as outdoor-unit eeprom failure.
The official NAA Air Conditioner Installation and Operation Manual identifies FB as driver-chip eeprom failure.
The official NAA Air Conditioner Installation and Operation Manual identifies FC as ipm module sensor error.
The official NAA Air Conditioner Installation and Operation Manual identifies FD as hlp pressure sensor failure.
The official NAA Air Conditioner Installation and Operation Manual identifies FE as t3 or t5 sensor disconnected.
The official NAA Air Conditioner Installation and Operation Manual identifies FF as hps condenser sensor disconnected.
The official NAA Air Conditioner Installation and Operation Manual identifies H0 as communication fault between the master board and driver chip.
The official NAA Air Conditioner Installation and Operation Manual identifies H1 as t3 sensor high temperature error after three p5 events within 180 minutes.
The official NAA Air Conditioner Installation and Operation Manual identifies H2 as high pressure switch error after three p1 events within 150 minutes.
The official NAA Air Conditioner Installation and Operation Manual identifies H4 as ipm module high temperature error after three p8 events within 120…
The official NAA Air Conditioner Installation and Operation Manual identifies H5 as low pressure error after five p2 events within 240 minutes.
The official NAA Air Conditioner Installation and Operation Manual identifies H6 as abnormal discharge temperature after three p4 events within 100 minutes.
The official NAA Air Conditioner Installation and Operation Manual identifies H7 as moisture exposure operation error after three pc events within 200…
The official NAA Air Conditioner Installation and Operation Manual identifies H8 as t3 condenser sensor disconnection after three fe events within 120…
The official NAA Air Conditioner Installation and Operation Manual identifies HC as discharge temperature sensor disconnection after three fe events within…
The official NAA Air Conditioner Installation and Operation Manual identifies HE as condensate error after three events within 60 minutes.
The official NAA Air Conditioner Installation and Operation Manual identifies L0 as low dc bus voltage protection.
The official NAA Air Conditioner Installation and Operation Manual identifies L1 as high dc bus voltage protection.
The official NAA Air Conditioner Installation and Operation Manual identifies LA as frequency limited by voltage.
The official NAA Air Conditioner Installation and Operation Manual identifies LB as frequency limited or reduced by high pressure.
The official NAA Air Conditioner Installation and Operation Manual identifies LC as frequency limited by condenser temperature.
The official NAA Air Conditioner Installation and Operation Manual identifies LD as frequency limited by discharge temperature.
The official NAA Air Conditioner Installation and Operation Manual identifies LE as frequency limited by high ipm module temperature.
The official NAA Air Conditioner Installation and Operation Manual identifies LF as frequency limited by current.
The official NAA Air Conditioner Installation and Operation Manual identifies P1 as high pressure switch error.
The official NAA Air Conditioner Installation and Operation Manual identifies P2 as low pressure protection.
The official NAA Air Conditioner Installation and Operation Manual identifies P3 as inverter overcurrent protection.
The official NAA Air Conditioner Installation and Operation Manual identifies P4 as high compressor discharge temperature protection at the t5 sensor.
The official NAA Air Conditioner Installation and Operation Manual identifies P5 as high condenser temperature protection at the t3 sensor.
The official NAA Air Conditioner Installation and Operation Manual identifies P6 as ipm protection.
The official NAA Air Conditioner Installation and Operation Manual identifies P8 as ipm high temperature protection (ft).
The official NAA Air Conditioner Installation and Operation Manual identifies P9 as dc fan motor error.
The official NAA Air Conditioner Installation and Operation Manual identifies PC as wet operation error.
The official NAA Air Conditioner Installation and Operation Manual identifies PRH as crankcase heater in progress; start-up is inhibited.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E001 as heat exchanger overheat.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E003 as ignition failure.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E004 as false flame.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E012 as flame loss.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E016 as heat exchanger overheat.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E030 as exhaust overheat.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E031 as burner overheat.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E046 as heat exchanger thermistor error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E047 as exhaust thermistor error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E060 as abnormal dual venturi.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E109 as abnormal fan motor.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E110 as exhaust blockage.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E205 as heating supply temperature sensor error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E218 as heating return temperature sensor error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E278 as external supply sensor not detected.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E279 as external return sensor not detected.
The official NFB-H Condensing Boilers Installation Manual identifies E291 as heating return temperature exceeds the heating supply temperature.
The official NFB-H Condensing Boilers Installation Manual identifies E302 as low water pressure.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E351 as abnormal automatic feeder valve.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E352 as high water pressure.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E353 as water pressure sensor error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E407 as domestic hot-water outlet sensor error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E421 as domestic cold-water inlet sensor error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E434 as abnormal water-adjustment valve.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E439 as no domestic water flow detected.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E441 as domestic hot-water outlet sensor 2 error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E445 as abnormal mixing valve.
The official NFB-H Condensing Boilers Installation Manual identifies E480 as domestic hot-water tank sensor not detected.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E515 as abnormal pcb.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E517 as abnormal dip switch.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E594 as abnormal eeprom.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E615 as abnormal memory.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E736 as cascade communication error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E740 as outdoor sensor not detected.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E761 as pump aquastat not detected.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E762 as vent pipe not fully inserted.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E773 as improper gas type detected.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E777 as low-water cutoff activated.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E782 as front-panel communication error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E784 as zone-controller communication error.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E786 as improper front panel.
The official NCB-H Condensing Combi-Boilers Installation and Operation Manual identifies E788 as incorrect gas-type setting.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E003 as ignition failure or clogged vents.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E004 as false flame. The official table associates it with subcode 00.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E012 as flame loss during combustion.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E016 as heat exchanger overheating.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E030 as abnormal exhaust gas temperature lockout.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E031 as burner overheating.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E046 as abnormal heat-exchanger limit-control operation.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E047-01 as abnormal exhaust temperature sensor operation at the lower…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E047-02 as abnormal exhaust temperature sensor operation at the upper…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E109 as abnormal inducer fan operation.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E205-01 as abnormal supply-water temperature sensor operation at the…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E205-02 as abnormal supply-water temperature sensor operation at the…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E218-01 as abnormal return-water temperature sensor operation at the…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E218-02 as abnormal return-water temperature sensor operation at the…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E238-01 as abnormal recirculation-pump operation: pump on with no…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E238-02 as abnormal recirculation-pump operation: pump off with water…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E302 as low water level.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E311 as abnormal water level.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E351 as abnormal water fill.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E360 as abnormal cover opening or abnormal ac 24 v transformer output.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E515-01 as abnormal wd-pss1 status.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E515-02 as abnormal wd-pss2 status.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E515-03 as abnormal mgv1 status.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E515-04 as abnormal mgv2 status.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E515-09 as abnormal fan control.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E515-10 as abnormal monitoring-device status.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E515-16 as abnormal aws feedback.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E515-24 as abnormal leakage input.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E517 as abnormal dip switch settings.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E593 as abnormal front-panel key.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E594 as abnormal eeprom operation.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E615-01 as abnormal overheat-controller feedback.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E615-03 as abnormal flame-signal input.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E615-04 as abnormal adc reference voltage.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E615-05 as abnormal mcu operation.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E740 as abnormal outdoor-temperature sensor operation.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E762 as improper vent-pipe installation.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E774 as abnormal external safety-system operation 1.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E775 as abnormal external safety-system operation 2.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E782 as abnormal controller-to-panel communication.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E786 as abnormal front control-panel connection.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E788 as abnormal gas-type settings.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E799-00 as leak detected by the leak sensor.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E799-01 as leak detected through the water-level condition.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E805-01 as abnormal supply-air temperature sensor operation at the…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E805-02 as abnormal supply-air temperature sensor operation at the…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E810 as abnormal circulator operation; ecm motor inoperable (subcodes…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E811 as abnormal circulator operation; circulator inoperable.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E818-01 as abnormal return-air temperature sensor operation at the…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E818-02 as abnormal return-air temperature sensor operation at the…
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E822 as air-conditioning evaporator coil overcooling.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E860-01 as circulator filter replacement alert.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E860-02 as humidifier-pad replacement alert.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E860-03 as uv-light replacement alert.
The official NPF Condensing Hydro-furnace Installation and Operation Manual identifies E890 as abnormal circulator communication.
Navien water heater E003 means Ignition failure. See the verified model scope, safe checks, and official source.
Navien water heater E004 means False flame detection. See the verified model scope, safe checks, and official source.
Navien water heater E012 means Flame loss. See the verified model scope, safe checks, and official source.
Navien water heater E016 means Overheating of the heat exchanger. See the verified model scope, safe checks, and official source.
Navien water heater E030 means Exhaust overheating - the water heater shuts down when the flue temperature exceeds 149 degrees F (65 degrees C).
Navien water heater E046 means Abnormal operation: limit control. See the verified model scope, safe checks, and official source.
Navien water heater E047 means Abnormal operation: exhaust thermostat. See the verified model scope, safe checks, and official source.
Navien water heater E060 means Abnormal operation: dual venturi. See the verified model scope, safe checks, and official source.
Navien water heater E109 means Abnormal operation: fan motor. See the verified model scope, safe checks, and official source.
Navien water heater E110 means Abnormal air pressure. See the verified model scope, safe checks, and official source.
Navien water heater E407 means Hot water outlet: thermistor open or short circuit.
Navien water heater E421 means Cold water inlet 1: thermistor open or short circuit.
Navien water heater E432 means Cold water inlet 2: thermistor open or short circuit.
Navien water heater E434 means Abnormal operation: water adjustment valve. See the verified model scope, safe checks, and official source.
Navien water heater E438 means Abnormal operation: circulation pump. See the verified model scope, safe checks, and official source.
Navien water heater E439 means Abnormal operation: flow sensor. See the verified model scope, safe checks, and official source.
Navien water heater E441 means Hot water inlet 2: thermistor open or short circuit.
Navien water heater E445 means Abnormal operation: bypass mixing valve. See the verified model scope, safe checks, and official source.
Navien water heater E515 means Abnormal operation: PCB (printed circuit board). See the verified model scope, safe checks, and official source.
Navien water heater E517 means Abnormal operation: DIP switch setting. See the verified model scope, safe checks, and official source.
Navien water heater E593 means Abnormal operation: front panel key. See the verified model scope, safe checks, and official source.
Navien water heater E615 means Abnormal operation: input and memory. See the verified model scope, safe checks, and official source.
Navien water heater E736 means Abnormal operation: cascade communication. See the verified model scope, safe checks, and official source.
Navien water heater E740 means Abnormal operation: outdoor temperature sensor. See the verified model scope, safe checks, and official source.
Navien water heater E760 means Flushing/service alarm. See the verified model scope, safe checks, and official source.
Navien water heater E782 means Abnormal operation: main panel communication. See the verified model scope, safe checks, and official source.
Navien water heater E785 means Abnormal operation: flow switch/sensor. See the verified model scope, safe checks, and official source.