Napoleon
Napoleon Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E01
Furnace will not start; control board shows E01 and inducer motor does not run
Pressure Switch Failed to Close on Call for Heat
E02
Furnace attempts to start but shuts down with E02; inducer runs but no ignition
Flame Not Detected / Ignition Failure
E03
Furnace starts, burners light briefly, then shut off with E03 code
Flame Loss During Run
E04
Furnace displays E04 and shuts down shortly after blower starts
High Limit Switch Open (Overtemperature)
E05
Furnace shows E05 and will not complete ignition sequence; inducer may start and stop repeatedly
Pressure Switch Stuck Open or Failed to Prove Draft
E06
Control board displays E06; furnace shuts down and may lock out after several attempts
Rollout Switch Open / Flame Rollout Detected
E07
Furnace displays E07 and blower runs continuously without heat
Low Limit / Fan Limit or Auxiliary Limit Open
E08
Furnace shows E08; inducer and blower may not run; no response to thermostat
24V Control Circuit Low Voltage or Short
E09
Furnace displays E09 and will not respond to thermostat commands
Internal Control Board Fault / EEPROM Error
E10
Furnace displays E10; the inducer may start, but burners do not light; this may indicate reversed polarity or a grounding issue.
Line Voltage Polarity / Ground Fault
E11
Furnace displays E11; the inducer runs continuously without ignition attempts.
Stuck Closed Pressure Switch
E12
Furnace displays E12; the blower may start, but burners do not ignite; this is often associated with limit circuit issues.
Open Limit Circuit Lockout
E13
Furnace displays E13; burners light, but the main blower does not start, then the unit overheats and shuts down.
Blower Motor Failure or Fan Relay Fault
E14
Furnace displays E14; the inducer does not start; no ignition attempts.
Inducer Motor Failure or Inducer Relay Fault
E15
Furnace displays E15; burners ignite but shut off quickly; this may indicate improper flame sensing or polarity.
Flame Sense Polarity / Microamp Signal Fault
E16
Furnace displays E16; the unit may lock out after multiple failed ignition attempts.
Ignition Lockout (Exceeded Retry Limit)
E17
Furnace displays E17; the blower runs at high speed continuously, with no heat.
Emergency Heat / Fault Mode – Limit or Board Failure
E18
Furnace displays E18; the unit may operate but with abnormal fan behavior or intermittent shutdowns.
ECM Blower Communication Error
E19
Furnace displays E19; the unit may shut down due to a condensate-related fault.
Condensate Overflow or Float Switch Open
E20
Furnace shows E20; unit may not respond to the thermostat or behaves erratically.
Thermostat Input Error
Symptom
Furnace blower runs continuously even when the thermostat is not calling for heat.
Continuous Fan Operation
Symptom
Furnace cycles on and off rapidly (every 1–5 minutes) without reaching the set temperature.
Rapid Cycling Due to Thermostat or Flame Sensing Issues
Symptom
Furnace frequently trips the household circuit breaker.
Electrical Overload or Short Circuit
Symptom
Furnace runs, but some rooms are much colder than others.
Uneven Heating / Airflow Imbalance
Symptom
Furnace runs, but the carbon monoxide detector in the home alarms.
Unsafe Combustion / Flue Gas Spillage
Symptom
Furnace starts normally but shuts off when the blower starts.
Flame Disturbance Due to Airflow
Symptom
The furnace causes a rotten egg or sulfur smell in the home.
Gas Leak or Combustion Problem
Symptom
The furnace emits a burning smell when running.
Overheating Components or Dust Burn-Off
Symptom
The furnace inducer runs, but the burners never ignite; no error code is displayed.
Silent Ignition Failure
Symptom
The furnace makes a loud banging or booming noise at startup.
Delayed Ignition / Burner Light-Off Problem
Symptom
The furnace produces a high-pitched whine or loud humming during operation.
Blower or Inducer Mechanical Noise
Symptom
The furnace runs but does not produce enough heat; the home never reaches the set temperature.
Underfiring or Insufficient Heat Output
Symptom
The furnace short cycles: it starts, runs for a few minutes, then shuts off and restarts frequently.
Short Cycling Due to Overheating or Thermostat Issues
Symptom
The furnace vibrates excessively and causes rattling in the ductwork.
Excessive Vibration / Imbalanced Blower Wheel
Symptom
The furnace will not start at all; there is no inducer, no blower, and no lights on the control board.
No Power to Furnace
Symptom
Thermostat calls for heat, but the furnace only clicks and never starts the inducer or blower.
Control Board Relay or Low-Voltage Control Fault
Symptom
Visible rust flakes or corrosion inside the furnace cabinet and on burners.
Corrosion Due to Condensate or Combustion Issues
Symptom
Water pooling around the base of the furnace.
Condensate Leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E01 |
Furnace will not start; control board shows E01 and inducer motor does not run
|
Pressure Switch Failed to Close on Call for Heat | View Details |
| E02 |
Furnace attempts to start but shuts down with E02; inducer runs but no ignition
|
Flame Not Detected / Ignition Failure | View Details |
| E03 |
Furnace starts, burners light briefly, then shut off with E03 code
|
Flame Loss During Run | View Details |
| E04 |
Furnace displays E04 and shuts down shortly after blower starts
|
High Limit Switch Open (Overtemperature) | View Details |
| E05 |
Furnace shows E05 and will not complete ignition sequence; inducer may start and stop repeatedly
|
Pressure Switch Stuck Open or Failed to Prove Draft | View Details |
| E06 |
Control board displays E06; furnace shuts down and may lock out after several attempts
|
Rollout Switch Open / Flame Rollout Detected | View Details |
| E07 |
Furnace displays E07 and blower runs continuously without heat
|
Low Limit / Fan Limit or Auxiliary Limit Open | View Details |
| E08 |
Furnace shows E08; inducer and blower may not run; no response to thermostat
|
24V Control Circuit Low Voltage or Short | View Details |
| E09 |
Furnace displays E09 and will not respond to thermostat commands
|
Internal Control Board Fault / EEPROM Error | View Details |
| E10 |
Furnace displays E10; the inducer may start, but burners do not light; this may indicate reversed polarity or a grounding issue.
|
Line Voltage Polarity / Ground Fault | View Details |
| E11 |
Furnace displays E11; the inducer runs continuously without ignition attempts.
|
Stuck Closed Pressure Switch | View Details |
| E12 |
Furnace displays E12; the blower may start, but burners do not ignite; this is often associated with limit circuit issues.
|
Open Limit Circuit Lockout | View Details |
| E13 |
Furnace displays E13; burners light, but the main blower does not start, then the unit overheats and shuts down.
|
Blower Motor Failure or Fan Relay Fault | View Details |
| E14 |
Furnace displays E14; the inducer does not start; no ignition attempts.
|
Inducer Motor Failure or Inducer Relay Fault | View Details |
| E15 |
Furnace displays E15; burners ignite but shut off quickly; this may indicate improper flame sensing or polarity.
|
Flame Sense Polarity / Microamp Signal Fault | View Details |
| E16 |
Furnace displays E16; the unit may lock out after multiple failed ignition attempts.
|
Ignition Lockout (Exceeded Retry Limit) | View Details |
| E17 |
Furnace displays E17; the blower runs at high speed continuously, with no heat.
|
Emergency Heat / Fault Mode – Limit or Board Failure | View Details |
| E18 |
Furnace displays E18; the unit may operate but with abnormal fan behavior or intermittent shutdowns.
|
ECM Blower Communication Error | View Details |
| E19 |
Furnace displays E19; the unit may shut down due to a condensate-related fault.
|
Condensate Overflow or Float Switch Open | View Details |
| E20 |
Furnace shows E20; unit may not respond to the thermostat or behaves erratically.
|
Thermostat Input Error | View Details |
| – |
Furnace blower runs continuously even when the thermostat is not calling for heat.
|
Continuous Fan Operation | View Details |
| – |
Furnace cycles on and off rapidly (every 1–5 minutes) without reaching the set temperature.
|
Rapid Cycling Due to Thermostat or Flame Sensing Issues | View Details |
| – |
Furnace frequently trips the household circuit breaker.
|
Electrical Overload or Short Circuit | View Details |
| – |
Furnace runs, but some rooms are much colder than others.
|
Uneven Heating / Airflow Imbalance | View Details |
| – |
Furnace runs, but the carbon monoxide detector in the home alarms.
|
Unsafe Combustion / Flue Gas Spillage | View Details |
| – |
Furnace starts normally but shuts off when the blower starts.
|
Flame Disturbance Due to Airflow | View Details |
| – |
The furnace causes a rotten egg or sulfur smell in the home.
|
Gas Leak or Combustion Problem | View Details |
| – |
The furnace emits a burning smell when running.
|
Overheating Components or Dust Burn-Off | View Details |
| – |
The furnace inducer runs, but the burners never ignite; no error code is displayed.
|
Silent Ignition Failure | View Details |
| – |
The furnace makes a loud banging or booming noise at startup.
|
Delayed Ignition / Burner Light-Off Problem | View Details |
| – |
The furnace produces a high-pitched whine or loud humming during operation.
|
Blower or Inducer Mechanical Noise | View Details |
| – |
The furnace runs but does not produce enough heat; the home never reaches the set temperature.
|
Underfiring or Insufficient Heat Output | View Details |
| – |
The furnace short cycles: it starts, runs for a few minutes, then shuts off and restarts frequently.
|
Short Cycling Due to Overheating or Thermostat Issues | View Details |
| – |
The furnace vibrates excessively and causes rattling in the ductwork.
|
Excessive Vibration / Imbalanced Blower Wheel | View Details |
| – |
The furnace will not start at all; there is no inducer, no blower, and no lights on the control board.
|
No Power to Furnace | View Details |
| – |
Thermostat calls for heat, but the furnace only clicks and never starts the inducer or blower.
|
Control Board Relay or Low-Voltage Control Fault | View Details |
| – |
Visible rust flakes or corrosion inside the furnace cabinet and on burners.
|
Corrosion Due to Condensate or Combustion Issues | View Details |
| – |
Water pooling around the base of the furnace.
|
Condensate Leak | View Details |
No matching codes found
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