Danfoss
Danfoss Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E0
Furnace will not start; controller display shows E0, and the burner never attempts to ignite.
No Call for Heat / Missing External Control Signal
E1
Furnace attempts to start but locks out with E1; no flame is established.
Ignition Failure / No Flame Establishment
E10
The furnace displays E10, indicating a communication error between the main Danfoss controller and a remote module (e.g., burner control or user interface).
Communication Bus Failure
E11
The furnace intermittently shuts down with E11, indicating a return air temperature sensor fault.
Return Air NTC Sensor Error
E12
The furnace displays E12 and will not fire, indicating an outdoor temperature sensor fault (for weather-compensated Danfoss systems).
Outdoor Sensor Failure / Open or Short Circuit
E13
The furnace locks out with E13, indicating a condensate drain or condensate level fault (for condensing furnaces with Danfoss controls).
Condensate Drain Blockage / Float Switch Trip
E14
The furnace displays E14, indicating a flue gas temperature sensor fault.
Flue Gas NTC Sensor Error
E15
The furnace shuts down with E15, indicating a flame detected when there should be no flame (false flame signal).
False Flame Detection / Flame Sensor Short Circuit
E16
The furnace displays E16, indicating a low voltage or power supply fault.
Mains Undervoltage / Power Quality Error
E17
The furnace displays E17 and stops, indicating an open safety chain or external interlock.
Safety Loop Open / External Interlock Fault
E18
The furnace intermittently locks out with E18 during windy conditions, and the burner stops unexpectedly.
Flue Draft / Wind Pressure Disturbance
E19
The furnace displays E19, indicating a modulation or gas valve positioning fault on a modulating Danfoss burner.
Gas Valve Modulation Error
E2
Furnace locks out with E2 shortly after ignition; flame appears briefly, then goes out.
Flame Loss During Run / Unstable Combustion
E3
Controller shows E3, and the burner does not start; the fan may run briefly, then stop.
Air Pressure Switch / Draft Prover Fault
E4
Furnace shuts down with E4, indicating a high-temperature warning; the burner stops, and the blower may continue running.
High Limit Switch Trip / Overheat Condition
E5
Furnace displays E5 and will not start, indicating an internal temperature sensor fault.
NTC Temperature Sensor Failure / Open or Short Circuit
E6
Controller shows E6; the burner stops and will not restart until reset, often after a power disturbance.
Control Board Internal Error / EEPROM or Configuration Fault
E7
Furnace shows E7 and shuts down, indicating a fan or blower fault.
Circulation Blower Motor Failure / Fan Speed Feedback Error
E8
Furnace displays E8; the burner shuts down due to low water or system pressure (for hydronic furnace/air handler combinations using Danfoss controls).
Low System Pressure / Water Flow Fault
E9
Furnace locks out with E9, indicating a gas valve or fuel valve fault.
Gas Valve Control Error / Fuel Valve Circuit Fault
Symptom
Furnace blower runs continuously even when there is no call for heat.
Blower Stuck in Manual/On Mode or Fan Relay Welded
Symptom
Furnace causes noticeable vibration and rattling in ducts and nearby walls.
Excessive Vibration / Imbalanced Blower Wheel
Symptom
Furnace frequently trips the circuit breaker or blows fuses.
Electrical Overload / Short Circuit
Symptom
Furnace makes loud banging or booming noises at startup.
Delayed Ignition / Combustion Instability
Symptom
Furnace produces a high-pitched whine or screeching noise during operation.
Blower or Inducer Motor Bearing Wear
Symptom
Furnace runs but produces no heat; supply air is cold or only slightly warm.
Burner Not Firing / Heat Exchanger Cold
Symptom
Furnace starts and stops frequently, with very short run times and uneven room temperatures.
Short Cycling Due to Oversizing or Control Settings
Symptom
Furnace starts but shuts off after a few seconds, repeatedly cycling without heating the space.
Short Cycling Due to Flame Loss or Limit Trip
Symptom
Strong fuel or exhaust smell around the furnace during operation.
Combustion Gas Leakage / Incomplete Combustion
Symptom
The furnace does not start at all; there are no lights on the Danfoss controller, and the blower and burner are inactive.
No Power to the Furnace
Symptom
The furnace fan runs, but there is little or no airflow from the registers.
Airflow Restriction / Blower Failure
Symptom
The furnace ignites, but the flame appears yellow and sooty instead of blue and stable.
Improper Combustion / Insufficient Air
Symptom
The furnace occasionally fails to start on very cold mornings but works later in the day.
Cold Start Issues / Marginal Ignition or Fuel Supply
Symptom
The furnace operates but makes a rumbling or roaring noise through the flue.
Flue Resonance / Draft Imbalance
Symptom
The furnace runs, but some rooms are too cold while others are too warm.
Airflow Imbalance / Duct Distribution Issue
Symptom
The furnace starts normally but shuts down after several minutes, with the blower continuing to run for a long time.
High Limit Cycling / Overheating
Symptom
Water leaking from the base of the furnace or around the condensate drain.
Condensate Leak / Drain Misrouting
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E0 |
Furnace will not start; controller display shows E0, and the burner never attempts to ignite.
|
No Call for Heat / Missing External Control Signal | View Details |
| E1 |
Furnace attempts to start but locks out with E1; no flame is established.
|
Ignition Failure / No Flame Establishment | View Details |
| E10 |
The furnace displays E10, indicating a communication error between the main Danfoss controller and a remote module (e.g., burner control or user interface).
|
Communication Bus Failure | View Details |
| E11 |
The furnace intermittently shuts down with E11, indicating a return air temperature sensor fault.
|
Return Air NTC Sensor Error | View Details |
| E12 |
The furnace displays E12 and will not fire, indicating an outdoor temperature sensor fault (for weather-compensated Danfoss systems).
|
Outdoor Sensor Failure / Open or Short Circuit | View Details |
| E13 |
The furnace locks out with E13, indicating a condensate drain or condensate level fault (for condensing furnaces with Danfoss controls).
|
Condensate Drain Blockage / Float Switch Trip | View Details |
| E14 |
The furnace displays E14, indicating a flue gas temperature sensor fault.
|
Flue Gas NTC Sensor Error | View Details |
| E15 |
The furnace shuts down with E15, indicating a flame detected when there should be no flame (false flame signal).
|
False Flame Detection / Flame Sensor Short Circuit | View Details |
| E16 |
The furnace displays E16, indicating a low voltage or power supply fault.
|
Mains Undervoltage / Power Quality Error | View Details |
| E17 |
The furnace displays E17 and stops, indicating an open safety chain or external interlock.
|
Safety Loop Open / External Interlock Fault | View Details |
| E18 |
The furnace intermittently locks out with E18 during windy conditions, and the burner stops unexpectedly.
|
Flue Draft / Wind Pressure Disturbance | View Details |
| E19 |
The furnace displays E19, indicating a modulation or gas valve positioning fault on a modulating Danfoss burner.
|
Gas Valve Modulation Error | View Details |
| E2 |
Furnace locks out with E2 shortly after ignition; flame appears briefly, then goes out.
|
Flame Loss During Run / Unstable Combustion | View Details |
| E3 |
Controller shows E3, and the burner does not start; the fan may run briefly, then stop.
|
Air Pressure Switch / Draft Prover Fault | View Details |
| E4 |
Furnace shuts down with E4, indicating a high-temperature warning; the burner stops, and the blower may continue running.
|
High Limit Switch Trip / Overheat Condition | View Details |
| E5 |
Furnace displays E5 and will not start, indicating an internal temperature sensor fault.
|
NTC Temperature Sensor Failure / Open or Short Circuit | View Details |
| E6 |
Controller shows E6; the burner stops and will not restart until reset, often after a power disturbance.
|
Control Board Internal Error / EEPROM or Configuration Fault | View Details |
| E7 |
Furnace shows E7 and shuts down, indicating a fan or blower fault.
|
Circulation Blower Motor Failure / Fan Speed Feedback Error | View Details |
| E8 |
Furnace displays E8; the burner shuts down due to low water or system pressure (for hydronic furnace/air handler combinations using Danfoss controls).
|
Low System Pressure / Water Flow Fault | View Details |
| E9 |
Furnace locks out with E9, indicating a gas valve or fuel valve fault.
|
Gas Valve Control Error / Fuel Valve Circuit Fault | View Details |
| – |
Furnace blower runs continuously even when there is no call for heat.
|
Blower Stuck in Manual/On Mode or Fan Relay Welded | View Details |
| – |
Furnace causes noticeable vibration and rattling in ducts and nearby walls.
|
Excessive Vibration / Imbalanced Blower Wheel | View Details |
| – |
Furnace frequently trips the circuit breaker or blows fuses.
|
Electrical Overload / Short Circuit | View Details |
| – |
Furnace makes loud banging or booming noises at startup.
|
Delayed Ignition / Combustion Instability | View Details |
| – |
Furnace produces a high-pitched whine or screeching noise during operation.
|
Blower or Inducer Motor Bearing Wear | View Details |
| – |
Furnace runs but produces no heat; supply air is cold or only slightly warm.
|
Burner Not Firing / Heat Exchanger Cold | View Details |
| – |
Furnace starts and stops frequently, with very short run times and uneven room temperatures.
|
Short Cycling Due to Oversizing or Control Settings | View Details |
| – |
Furnace starts but shuts off after a few seconds, repeatedly cycling without heating the space.
|
Short Cycling Due to Flame Loss or Limit Trip | View Details |
| – |
Strong fuel or exhaust smell around the furnace during operation.
|
Combustion Gas Leakage / Incomplete Combustion | View Details |
| – |
The furnace does not start at all; there are no lights on the Danfoss controller, and the blower and burner are inactive.
|
No Power to the Furnace | View Details |
| – |
The furnace fan runs, but there is little or no airflow from the registers.
|
Airflow Restriction / Blower Failure | View Details |
| – |
The furnace ignites, but the flame appears yellow and sooty instead of blue and stable.
|
Improper Combustion / Insufficient Air | View Details |
| – |
The furnace occasionally fails to start on very cold mornings but works later in the day.
|
Cold Start Issues / Marginal Ignition or Fuel Supply | View Details |
| – |
The furnace operates but makes a rumbling or roaring noise through the flue.
|
Flue Resonance / Draft Imbalance | View Details |
| – |
The furnace runs, but some rooms are too cold while others are too warm.
|
Airflow Imbalance / Duct Distribution Issue | View Details |
| – |
The furnace starts normally but shuts down after several minutes, with the blower continuing to run for a long time.
|
High Limit Cycling / Overheating | View Details |
| – |
Water leaking from the base of the furnace or around the condensate drain.
|
Condensate Leak / Drain Misrouting | View Details |
No matching codes found
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