Daikin Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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A1
Daikin furnace shows A1; unit may not respond to thermostat commands or may lock out.
Indoor Unit Main PCB Failure
A3
Daikin furnace/air handler shows A3; unit may shut down on condensate fault, especially in high-efficiency models with PVC venting.
Condensate Drain Level / Float Switch Trip
A5
Daikin furnace/air handler shows A5; unit may shut down shortly after starting, often on high heat or with restricted airflow.
Indoor Heat Exchanger / Coil Overheat Protection
A6
Daikin furnace/air handler shows A6; indoor fan does not run or runs erratically, no airflow during heating.
Indoor Fan Motor Fault
C4
Daikin furnace shows C4; unit may not start or may shut down unexpectedly.
Faulty Return Air Thermistor / Temperature Sensor
C9
Daikin furnace shows C9; unit may operate erratically or shut down on temperature sensing error.
Faulty Indoor Coil / Discharge Air Thermistor
E0
Daikin furnace shows E0; unit may not respond to thermostat or may be locked out.
Indoor Unit EEPROM / Configuration Error
E3
Daikin furnace shows E3; unit may shut down on high temperature or fail to complete a heating cycle.
High Discharge Air Temperature / Overheat
E5
Daikin furnace shows E5; unit may not start or may shut down on safety fault.
Overcurrent / Power Supply Protection
H0
Daikin furnace shows H0; unit may not start or may run in a limited mode.
Indoor Unit Capacity / Model Mismatch or Configuration Error
H6
Daikin furnace/air handler shows H6; indoor fan may run at incorrect speed or not at all.
Indoor Fan Motor Lock / Stall Detection
L3
Daikin furnace displays L3; unit may shut down during operation, sometimes after running for a short period.
Abnormal Compressor/Fan Current or Overcurrent (applied to furnace/air handler fan section)
L5
Daikin furnace shows L5; unit may lock out on repeated overcurrent or protection events.
Lockout Due to Repeated Overcurrent / Protection Trips
U0
Daikin gas furnace will not start; control board shows U0, inducer may start briefly then stop, no ignition.
Insufficient Gas Supply / Gas Valve Lockout
U2
Daikin furnace intermittently shuts down with U2 error; blower may run but no heat, or unit locks out after several attempts.
Low Voltage / Power Supply Error
U4
Daikin furnace shows U4 and will not run; communication thermostat may be blank or show communication error.
Communication Error Between Indoor Unit and Controller/Thermostat
U7
Daikin furnace/air handler shows U7; system may not coordinate properly with outdoor unit in a matched system.
Indoor–Outdoor Unit Mismatch / Communication Error
Symptom
Daikin furnace blower runs continuously even when there is no call for heat or fan from the thermostat.
Stuck Fan Relay / Fan On Due to Fault
Symptom
Daikin furnace burners light but shut off after a few seconds; blower may or may not start.
Flame Sensing Failure
Symptom
Daikin furnace causes noticeable vibration and noise transmitted through the ductwork and structure.
Mechanical Vibration / Poor Isolation
Symptom
Daikin furnace cycles on and off frequently (short cycling), with room temperature never reaching the thermostat setpoint.
Short Cycling Due to Oversizing or Safety Trips
Symptom
Daikin furnace emits a burning smell when first started or after a long period of no use.
Dust Burn-Off / Overheating Components
Symptom
Daikin furnace emits a strong chemical or plastic smell during operation.
Overheating Plastic Components or Contaminants in Ducts
Symptom
Daikin furnace frequently trips the household circuit breaker.
Overcurrent / Short Circuit in Furnace
Symptom
Daikin furnace inducer does not start; no ignition sequence begins, but control board has power.
Inducer Motor Failure / Pressure Switch Not Proving
Symptom
Daikin furnace inducer runs but burners do not light; after several tries the unit locks out with no specific code on a basic board.
Ignition Failure / No Flame Establishment
Symptom
Daikin furnace makes loud booming or rumbling noises at burner ignition.
Delayed Ignition / Burner Light-Off Problem
Symptom
Daikin furnace makes loud rattling or vibration noises when the blower is running.
Blower Wheel Imbalance / Loose Components
Symptom
Daikin furnace occasionally emits a faint gas smell near the unit during operation or shortly after shutdown.
Minor Gas Leakage or Incomplete Combustion
Symptom
Daikin furnace produces a high-pitched whine or grinding noise from the inducer area during operation.
Worn Draft Inducer Motor Bearings
Symptom
Daikin furnace produces heat but the blower never starts; heat exchanger becomes very hot and unit may trip on high limit.
Blower Motor Not Running
Symptom
Daikin furnace runs but gas consumption seems unusually high and efficiency appears poor.
Reduced Combustion Efficiency / Poor Heat Transfer
Symptom
Daikin furnace runs but some rooms are too cold while others are too warm.
Airflow Imbalance / Duct Distribution Issue
Symptom
Daikin furnace runs inducer and ignites but shuts down on high limit; unit may short-cycle with very hot supply air.
High Limit Switch Trip / Overheating Heat Exchanger
Symptom
Daikin furnace will not respond to thermostat; thermostat appears normal but no heating occurs.
Control Signal / Thermostat Circuit Failure
Symptom
Daikin gas furnace will not start at all; no inducer, no ignition, no blower, but power is present at the outlet.
No Power Through Furnace Safety Circuit
Symptom
Daikin high-efficiency furnace is leaking water around the base or inside the cabinet.
Condensate Leak from Secondary Heat Exchanger or Drain System
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A1 |
Daikin furnace shows A1; unit may not respond to thermostat commands or may lock out.
|
Indoor Unit Main PCB Failure | View Details |
| A3 |
Daikin furnace/air handler shows A3; unit may shut down on condensate fault, especially in high-efficiency models with PVC venting.
|
Condensate Drain Level / Float Switch Trip | View Details |
| A5 |
Daikin furnace/air handler shows A5; unit may shut down shortly after starting, often on high heat or with restricted airflow.
|
Indoor Heat Exchanger / Coil Overheat Protection | View Details |
| A6 |
Daikin furnace/air handler shows A6; indoor fan does not run or runs erratically, no airflow during heating.
|
Indoor Fan Motor Fault | View Details |
| C4 |
Daikin furnace shows C4; unit may not start or may shut down unexpectedly.
|
Faulty Return Air Thermistor / Temperature Sensor | View Details |
| C9 |
Daikin furnace shows C9; unit may operate erratically or shut down on temperature sensing error.
|
Faulty Indoor Coil / Discharge Air Thermistor | View Details |
| E0 |
Daikin furnace shows E0; unit may not respond to thermostat or may be locked out.
|
Indoor Unit EEPROM / Configuration Error | View Details |
| E3 |
Daikin furnace shows E3; unit may shut down on high temperature or fail to complete a heating cycle.
|
High Discharge Air Temperature / Overheat | View Details |
| E5 |
Daikin furnace shows E5; unit may not start or may shut down on safety fault.
|
Overcurrent / Power Supply Protection | View Details |
| H0 |
Daikin furnace shows H0; unit may not start or may run in a limited mode.
|
Indoor Unit Capacity / Model Mismatch or Configuration Error | View Details |
| H6 |
Daikin furnace/air handler shows H6; indoor fan may run at incorrect speed or not at all.
|
Indoor Fan Motor Lock / Stall Detection | View Details |
| L3 |
Daikin furnace displays L3; unit may shut down during operation, sometimes after running for a short period.
|
Abnormal Compressor/Fan Current or Overcurrent (applied to furnace/air handler fan section) | View Details |
| L5 |
Daikin furnace shows L5; unit may lock out on repeated overcurrent or protection events.
|
Lockout Due to Repeated Overcurrent / Protection Trips | View Details |
| U0 |
Daikin gas furnace will not start; control board shows U0, inducer may start briefly then stop, no ignition.
|
Insufficient Gas Supply / Gas Valve Lockout | View Details |
| U2 |
Daikin furnace intermittently shuts down with U2 error; blower may run but no heat, or unit locks out after several attempts.
|
Low Voltage / Power Supply Error | View Details |
| U4 |
Daikin furnace shows U4 and will not run; communication thermostat may be blank or show communication error.
|
Communication Error Between Indoor Unit and Controller/Thermostat | View Details |
| U7 |
Daikin furnace/air handler shows U7; system may not coordinate properly with outdoor unit in a matched system.
|
Indoor–Outdoor Unit Mismatch / Communication Error | View Details |
| – |
Daikin furnace blower runs continuously even when there is no call for heat or fan from the thermostat.
|
Stuck Fan Relay / Fan On Due to Fault | View Details |
| – |
Daikin furnace burners light but shut off after a few seconds; blower may or may not start.
|
Flame Sensing Failure | View Details |
| – |
Daikin furnace causes noticeable vibration and noise transmitted through the ductwork and structure.
|
Mechanical Vibration / Poor Isolation | View Details |
| – |
Daikin furnace cycles on and off frequently (short cycling), with room temperature never reaching the thermostat setpoint.
|
Short Cycling Due to Oversizing or Safety Trips | View Details |
| – |
Daikin furnace emits a burning smell when first started or after a long period of no use.
|
Dust Burn-Off / Overheating Components | View Details |
| – |
Daikin furnace emits a strong chemical or plastic smell during operation.
|
Overheating Plastic Components or Contaminants in Ducts | View Details |
| – |
Daikin furnace frequently trips the household circuit breaker.
|
Overcurrent / Short Circuit in Furnace | View Details |
| – |
Daikin furnace inducer does not start; no ignition sequence begins, but control board has power.
|
Inducer Motor Failure / Pressure Switch Not Proving | View Details |
| – |
Daikin furnace inducer runs but burners do not light; after several tries the unit locks out with no specific code on a basic board.
|
Ignition Failure / No Flame Establishment | View Details |
| – |
Daikin furnace makes loud booming or rumbling noises at burner ignition.
|
Delayed Ignition / Burner Light-Off Problem | View Details |
| – |
Daikin furnace makes loud rattling or vibration noises when the blower is running.
|
Blower Wheel Imbalance / Loose Components | View Details |
| – |
Daikin furnace occasionally emits a faint gas smell near the unit during operation or shortly after shutdown.
|
Minor Gas Leakage or Incomplete Combustion | View Details |
| – |
Daikin furnace produces a high-pitched whine or grinding noise from the inducer area during operation.
|
Worn Draft Inducer Motor Bearings | View Details |
| – |
Daikin furnace produces heat but the blower never starts; heat exchanger becomes very hot and unit may trip on high limit.
|
Blower Motor Not Running | View Details |
| – |
Daikin furnace runs but gas consumption seems unusually high and efficiency appears poor.
|
Reduced Combustion Efficiency / Poor Heat Transfer | View Details |
| – |
Daikin furnace runs but some rooms are too cold while others are too warm.
|
Airflow Imbalance / Duct Distribution Issue | View Details |
| – |
Daikin furnace runs inducer and ignites but shuts down on high limit; unit may short-cycle with very hot supply air.
|
High Limit Switch Trip / Overheating Heat Exchanger | View Details |
| – |
Daikin furnace will not respond to thermostat; thermostat appears normal but no heating occurs.
|
Control Signal / Thermostat Circuit Failure | View Details |
| – |
Daikin gas furnace will not start at all; no inducer, no ignition, no blower, but power is present at the outlet.
|
No Power Through Furnace Safety Circuit | View Details |
| – |
Daikin high-efficiency furnace is leaking water around the base or inside the cabinet.
|
Condensate Leak from Secondary Heat Exchanger or Drain System | View Details |
No matching codes found
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