Navien
Navien Water Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E001
Navien tankless water heater will not ignite; display shows E001 shortly after a hot water tap is opened.
Ignition Failure / Flame Detection Fault
E002
Navien water heater shuts down with E002; burner lights briefly or not at all and then unit locks out.
Low Gas Pressure / Gas Supply Fault
E003
Unit displays E003 and shuts down; burner may start and then stop, or may not start at all.
Ignition / Flame Loss During Operation
E004
Navien water heater shows E004 and will not run; often associated with power issues or control failure.
Control Board / Power Supply Fault
E012
Display shows E012; unit may attempt to start but shuts down quickly.
Flame Loss / Low Flame Signal
E016
Navien water heater displays E016 and shuts down during operation, often after running for some time.
Overheating / Heat Exchanger Over-Temperature
E021
Unit shows E021 and will not operate; often associated with fan or air pressure issues.
Air Pressure Switch / Fan Failure
E027
Navien water heater displays E027 and stops; often occurs during or after ignition attempts.
Fan Motor / RPM Feedback Fault
E030
Display shows E030; unit may not start or may shut down unexpectedly.
Exhaust Overheat / Flue Gas Temperature Fault
E032
Navien unit shows E032 and stops; often related to water flow sensing.
Flow Sensor / Flow Switch Fault
E035
Display shows E035; unit may not fire or may shut down intermittently.
Gas Valve / Combustion Control Fault
E038
Navien water heater shows E038; unit may lock out and not restart.
Condensate Drain / Pressure Fault
E046
Display shows E046; unit may not respond to thermostat or internal controls properly.
Communication Error Between Main PCB and Front Panel / Remote
E051
Navien unit displays E051 and stops; often related to water temperature sensing.
Inlet Water Temperature Sensor Fault
E052
Display shows E052; unit may overheat or behave erratically with outlet temperature.
Outlet Water Temperature Sensor Fault
E060
Navien water heater shows E060; unit may not start or may shut down quickly.
Recirculation Pump / Internal Pump Fault
E109
Display shows E109; unit may not fire or may shut down intermittently.
Fan Motor / Combustion Air Fault (Alternate Code)
E110
Navien unit displays E110; often associated with high exhaust or flue temperature.
Flue Overheat / High Limit Fault
E127
Display shows E127; unit may not respond correctly to temperature settings.
Outdoor Temperature Sensor Fault (for models with outdoor reset)
E302
Navien water heater shows E302; unit may lock out and require reset.
Low Water Pressure / Flow Fault
E352
Display shows E352; unit may not start or may shut down unexpectedly.
Internal Communication / PCB Fault
E407
Navien unit displays E407; often associated with DHW outlet sensor or mixing issues.
Domestic Hot Water Outlet Sensor / Mixing Fault
E421
Display shows E421; unit may not respond to external controls properly.
External Control / Thermostat Communication Fault
E432
Navien water heater shows E432; unit may lock out.
Return Water Temperature Sensor Fault (combi / heating models)
E438
Display shows E438; unit may not modulate or control temperature correctly.
Supply Water Temperature Sensor Fault (heating circuit)
E445
Navien unit displays E445; may be accompanied by erratic operation.
Internal Sensor Calibration / PCB Fault
Symptom
Hot water takes a very long time to reach fixtures even though the Navien has a built-in or external recirculation system.
Recirculation Performance Issue
Symptom
Intermittent hot water: temperature fluctuates between hot and cold during a shower without any error code.
Temperature Fluctuation / Short Cycling
Symptom
Navien water heater display shows normal operation but actual outlet water temperature is much hotter than the setpoint.
Overheating / Temperature Overshoot Without Code
Symptom
Navien water heater frequently shuts off and restarts while hot water is running, causing brief interruptions.
Short Cycling During Demand
Symptom
Navien water heater is excessively noisy with a high-pitched whine or grinding sound from inside the unit.
Fan or Pump Mechanical Noise
Symptom
Navien water heater is leaking condensate (clear water) from the bottom or from vent connections.
Condensate Leak / Drain Misrouting
Symptom
Navien water heater is leaking water from the bottom of the unit or from internal components; no error code displayed.
Internal Water Leak
Symptom
Navien water heater makes loud banging or knocking noises during operation, especially when the burner is firing.
Water Hammer / Combustion or Scale Noise
Symptom
Navien water heater trips the circuit breaker or GFCI when it attempts to start.
Electrical Short / Ground Fault
Symptom
Navien water heater vibrates excessively or rattles the wall during operation.
Excessive Vibration / Mounting Issue
Symptom
Navien water heater will not power on at all; display is blank and unit appears dead.
No Power / Electrical Supply Failure
Symptom
No hot water at any faucet; Navien tankless water heater display is on but burner does not fire and no error code is shown.
No Ignition Without Error Code
Symptom
Strong exhaust or burning smell near the Navien water heater or vent termination during operation; no error code.
Combustion Odor / Venting Issue
Symptom
Water is warm but not hot enough even when the Navien setpoint is at maximum; no error code displayed.
Insufficient Hot Water Temperature
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E001 |
Navien tankless water heater will not ignite; display shows E001 shortly after a hot water tap is opened.
|
Ignition Failure / Flame Detection Fault | View Details |
| E002 |
Navien water heater shuts down with E002; burner lights briefly or not at all and then unit locks out.
|
Low Gas Pressure / Gas Supply Fault | View Details |
| E003 |
Unit displays E003 and shuts down; burner may start and then stop, or may not start at all.
|
Ignition / Flame Loss During Operation | View Details |
| E004 |
Navien water heater shows E004 and will not run; often associated with power issues or control failure.
|
Control Board / Power Supply Fault | View Details |
| E012 |
Display shows E012; unit may attempt to start but shuts down quickly.
|
Flame Loss / Low Flame Signal | View Details |
| E016 |
Navien water heater displays E016 and shuts down during operation, often after running for some time.
|
Overheating / Heat Exchanger Over-Temperature | View Details |
| E021 |
Unit shows E021 and will not operate; often associated with fan or air pressure issues.
|
Air Pressure Switch / Fan Failure | View Details |
| E027 |
Navien water heater displays E027 and stops; often occurs during or after ignition attempts.
|
Fan Motor / RPM Feedback Fault | View Details |
| E030 |
Display shows E030; unit may not start or may shut down unexpectedly.
|
Exhaust Overheat / Flue Gas Temperature Fault | View Details |
| E032 |
Navien unit shows E032 and stops; often related to water flow sensing.
|
Flow Sensor / Flow Switch Fault | View Details |
| E035 |
Display shows E035; unit may not fire or may shut down intermittently.
|
Gas Valve / Combustion Control Fault | View Details |
| E038 |
Navien water heater shows E038; unit may lock out and not restart.
|
Condensate Drain / Pressure Fault | View Details |
| E046 |
Display shows E046; unit may not respond to thermostat or internal controls properly.
|
Communication Error Between Main PCB and Front Panel / Remote | View Details |
| E051 |
Navien unit displays E051 and stops; often related to water temperature sensing.
|
Inlet Water Temperature Sensor Fault | View Details |
| E052 |
Display shows E052; unit may overheat or behave erratically with outlet temperature.
|
Outlet Water Temperature Sensor Fault | View Details |
| E060 |
Navien water heater shows E060; unit may not start or may shut down quickly.
|
Recirculation Pump / Internal Pump Fault | View Details |
| E109 |
Display shows E109; unit may not fire or may shut down intermittently.
|
Fan Motor / Combustion Air Fault (Alternate Code) | View Details |
| E110 |
Navien unit displays E110; often associated with high exhaust or flue temperature.
|
Flue Overheat / High Limit Fault | View Details |
| E127 |
Display shows E127; unit may not respond correctly to temperature settings.
|
Outdoor Temperature Sensor Fault (for models with outdoor reset) | View Details |
| E302 |
Navien water heater shows E302; unit may lock out and require reset.
|
Low Water Pressure / Flow Fault | View Details |
| E352 |
Display shows E352; unit may not start or may shut down unexpectedly.
|
Internal Communication / PCB Fault | View Details |
| E407 |
Navien unit displays E407; often associated with DHW outlet sensor or mixing issues.
|
Domestic Hot Water Outlet Sensor / Mixing Fault | View Details |
| E421 |
Display shows E421; unit may not respond to external controls properly.
|
External Control / Thermostat Communication Fault | View Details |
| E432 |
Navien water heater shows E432; unit may lock out.
|
Return Water Temperature Sensor Fault (combi / heating models) | View Details |
| E438 |
Display shows E438; unit may not modulate or control temperature correctly.
|
Supply Water Temperature Sensor Fault (heating circuit) | View Details |
| E445 |
Navien unit displays E445; may be accompanied by erratic operation.
|
Internal Sensor Calibration / PCB Fault | View Details |
| – |
Hot water takes a very long time to reach fixtures even though the Navien has a built-in or external recirculation system.
|
Recirculation Performance Issue | View Details |
| – |
Intermittent hot water: temperature fluctuates between hot and cold during a shower without any error code.
|
Temperature Fluctuation / Short Cycling | View Details |
| – |
Navien water heater display shows normal operation but actual outlet water temperature is much hotter than the setpoint.
|
Overheating / Temperature Overshoot Without Code | View Details |
| – |
Navien water heater frequently shuts off and restarts while hot water is running, causing brief interruptions.
|
Short Cycling During Demand | View Details |
| – |
Navien water heater is excessively noisy with a high-pitched whine or grinding sound from inside the unit.
|
Fan or Pump Mechanical Noise | View Details |
| – |
Navien water heater is leaking condensate (clear water) from the bottom or from vent connections.
|
Condensate Leak / Drain Misrouting | View Details |
| – |
Navien water heater is leaking water from the bottom of the unit or from internal components; no error code displayed.
|
Internal Water Leak | View Details |
| – |
Navien water heater makes loud banging or knocking noises during operation, especially when the burner is firing.
|
Water Hammer / Combustion or Scale Noise | View Details |
| – |
Navien water heater trips the circuit breaker or GFCI when it attempts to start.
|
Electrical Short / Ground Fault | View Details |
| – |
Navien water heater vibrates excessively or rattles the wall during operation.
|
Excessive Vibration / Mounting Issue | View Details |
| – |
Navien water heater will not power on at all; display is blank and unit appears dead.
|
No Power / Electrical Supply Failure | View Details |
| – |
No hot water at any faucet; Navien tankless water heater display is on but burner does not fire and no error code is shown.
|
No Ignition Without Error Code | View Details |
| – |
Strong exhaust or burning smell near the Navien water heater or vent termination during operation; no error code.
|
Combustion Odor / Venting Issue | View Details |
| – |
Water is warm but not hot enough even when the Navien setpoint is at maximum; no error code displayed.
|
Insufficient Hot Water Temperature | View Details |
No matching codes found
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