Navien

Navien Boilers Error Codes

Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.

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E001
Boiler will not ignite and displays E001 on the control panel
Ignition Failure / Flame Not Established
E002
Boiler shuts down with E002 and does not fire, often after attempting ignition
Low Water Pressure / Flow Switch Fault
E003
Boiler locks out with E003 shortly after ignition attempt, sometimes with brief flame
Ignition / Flame Loss During Operation
E004
Boiler displays E004 and will not start, often accompanied by fan running briefly
Air Pressure Switch / Combustion Air Proving Failure
E005
Boiler shows E005 and shuts down during operation, often with high temperature readings
Overheating / High Limit Trip
E006
Boiler displays E006 and stops heating, often associated with low temperature readings or sensor error
Outlet Water Temperature Sensor Fault
E007
Boiler shows E007 and will not operate, often immediately at startup
Inlet Water Temperature Sensor Fault
E010
Boiler displays E010 and shuts down, often during or after a heating cycle
Abnormal Air Pressure / Fan or Venting Fault
E011
Boiler shows E011 and will not fire, often after fan starts
Air Pressure Switch Stuck or Out of Range
E012
Boiler intermittently shuts down with E012, often during high demand
Flame Loss / Unstable Combustion
E016
Boiler displays E016 and stops heating, often after running for some time
Overheat / Outlet Temperature Too High
E018
Boiler shows E018 and will not operate, often after a power event
Low Voltage / Power Supply Error
E020
Boiler displays E020 and stops, often with no circulation in the system
Circulation Pump Fault
E027
Boiler shows E027 and locks out, often immediately at startup
Exhaust Overheat / Flue Gas Temperature Too High
E030
Boiler intermittently displays E030 and stops heating
Outdoor Temperature Sensor Fault (if equipped)
E046
Boiler shows E046 and will not operate, often after configuration changes
Communication Error Between Main PCB and Front Panel / Add‑On Module
E060
Boiler displays E060 and stops, often with no response to thermostat calls
Thermostat / Room Controller Input Fault
E109
Boiler shows E109 and locks out, often during ignition attempts
Gas Valve / Gas Supply Error
E110
Boiler intermittently displays E110 and stops heating, often during long runs
Return Water Temperature Sensor Fault
E127
Boiler shows E127 and will not operate, often after service work
Internal Configuration / Parameter Error
E302
Boiler displays E302 and locks out, often with no ignition attempt
Flame Detection Error (Flame Present When Not Commanded)
E407
Boiler shows E407 and will not operate, often after connecting external controls
Communication Error with External Controller / Cascade Manager
Symptom
Boiler condensate trap overflows or water drips from bottom during operation
Condensate Drainage Failure
Symptom
Boiler cycles on but quickly shuts off with gurgling sounds inside unit
Air in Heat Exchanger / Poor Circulation
Symptom
Boiler display is on but unresponsive or buttons do not work reliably
Control Panel / User Interface Failure
Symptom
Boiler frequently goes to lockout with random error codes after lightning or power surges
Surge Damage / Intermittent Control Fault
Symptom
Boiler frequently loses pressure and needs to be topped up
Chronic Pressure Loss / System Leak
Symptom
Boiler is very noisy with high‑pitched whine or rumble during operation
Combustion or Fan Noise
Symptom
Boiler leaking water from bottom of cabinet
Internal Water Leak
Symptom
Boiler locks out frequently during very cold weather but no specific error code is shown
Freeze Protection / Low Temperature Lockout
Symptom
Boiler makes loud banging or knocking noises when starting or stopping
Water Hammer / Thermal Expansion Noise
Symptom
Boiler pressure gauge frequently rises above 30 psi and relief valve discharges water
System Overpressure
Symptom
Boiler produces a strong exhaust or burning smell near the unit
Combustion / Venting Odor Issue
Symptom
Boiler runs but radiators or in‑floor loops stay lukewarm or cold
Insufficient Space Heating Output
Symptom
Boiler short cycles (turns on and off frequently) during heating
Short Cycling / Control or System Imbalance
Symptom
Boiler will not start at all, display is blank
No Power / Dead Control
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