Carrier Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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11
No ignition, the furnace does not light, and the status LED shows code 11 (no previous code stored).
No Previous Fault Stored / Control Power Reset
12
The furnace attempts to start but stops, and the LED shows code 12 (blower on after power up).
Blower On After Power Up
13
The furnace locks out, and the LED shows code 13 (limit circuit lockout). The blower may run continuously, with the burners off.
Limit Circuit Lockout
14
The furnace attempts ignition but fails, and the LED shows code 14 (ignition lockout). The furnace may retry after an hour.
Ignition Lockout
21
Furnace LED shows code 21 (gas heating lockout), no heat; the blower may run for a short time then stop.
Gas Heating Lockout
23
Furnace LED shows code 23 (pressure switch did not open); the inducer may run continuously even with no call for heat.
Pressure Switch Stuck Closed
24
Furnace LED shows code 24 (secondary voltage fuse is open); no operation, and the thermostat appears dead.
Low-Voltage Fuse Open
31
Furnace LED shows code 31 (pressure, draft safeguard, or auxiliary limit switch open). The inducer may run, but burners do not light.
Pressure or Draft Fault
32
Furnace LED shows code 32 (low heat pressure switch did not close or reopened). The furnace may start, then shut down.
Low Heat Pressure Switch Fault
33
Furnace LED shows code 33 (limit or flame rollout switch open). The blower may run continuously, but the burners are off.
Open Limit or Rollout Circuit
34
Furnace LED shows code 34 (ignition proving failure). The ignitor glows, and burners may light briefly then go out.
Ignition Proving Failure
41
Furnace LED shows code 41 (blower motor fault). The blower may not start, may run at the wrong speed, or may be noisy.
Indoor Blower Motor Fault
42
Furnace LED shows code 42 (inducer motor fault). The furnace will not ignite; the inducer may not start or may start then stop.
Inducer Motor Fault
43
Furnace LED shows code 43 (pressure switch calibration fault or limit circuit fault, depending on the model).
Pressure Switch Calibration / Limit Fault
44
Furnace LED shows code 44 (secondary or auxiliary limit switch open). The furnace may run briefly, then shut down, while the blower continues to operate.
Auxiliary Limit Open
45
Furnace LED shows code 45 (control circuit lockout). The furnace is non-responsive until power is cycled.
Control Circuit Lockout
51
Furnace LED shows code 51 (gas valve relay fault). The furnace will not open the gas valve; no flame.
Gas Valve Relay Fault
55
Furnace LED shows code 55 (flame sensed with gas valve off). The furnace may shut down and lock out.
False Flame Sense
Symptom
A burning dust smell when the furnace first starts after a long off period.
Dust Burn-Off
Symptom
A strong chemical or metallic burning smell during furnace operation.
Overheating Components / Electrical Burn
Symptom
Furnace occasionally trips the household circuit breaker.
Overcurrent / Electrical Short
Symptom
Furnace starts normally but shuts off when the blower comes on.
Blower-Induced Flame Disturbance or Voltage Drop
Symptom
Some rooms are too hot while others are too cold when the Carrier furnace runs.
Uneven Heating / Airflow Imbalance
Symptom
The furnace blower runs continuously even when there is no call for heat or fan from the thermostat.
Continuous Fan Operation
Symptom
The furnace cycles on and off frequently (every few minutes), but the house never reaches the set temperature.
Thermostat or Sizing-Related Short Cycling
Symptom
The furnace ignites but the flame appears mostly yellow or orange and may produce soot.
Improper Combustion / Yellow Flame
Symptom
The furnace makes a loud banging or booming noise at startup when the burners ignite.
Delayed Ignition / Burner Flashback
Symptom
The furnace produces a high-pitched whine or screeching noise during operation.
Blower or Inducer Mechanical Noise
Symptom
The furnace runs but produces no warm air; the blower operates, but the supply air is cool or only slightly warm.
Burners Not Firing / No Heat Output
Symptom
The furnace runs but the blower airflow is weak from the registers.
Reduced Airflow
Symptom
The furnace short cycles: burners ignite and run for 30–90 seconds, then shut off, restarting frequently.
Short Cycling Due to Overheating or Flame Loss
Symptom
The furnace starts, runs for a while, then shuts off and will not restart for an hour or more.
Soft Lockout Due to Repeated Faults
Symptom
The furnace vibrates excessively or rattles the ductwork when running.
Excessive Vibration / Loose Components
Symptom
The furnace will not start at all; no inducer, no blower, and no LED lights on the control board.
No Power to Furnace
Symptom
Thermostat calls for heat but Carrier furnace does not respond; LED shows normal idle, no fault codes.
No Call for Heat Reaching Furnace
Symptom
Water is dripping from the metal vent pipe on a standard-efficiency (metal vented) Carrier furnace.
Flue Condensation
Symptom
Water is leaking around the base of a high-efficiency (PVC vented) Carrier furnace.
Condensate Leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| 11 |
No ignition, the furnace does not light, and the status LED shows code 11 (no previous code stored).
|
No Previous Fault Stored / Control Power Reset | View Details |
| 12 |
The furnace attempts to start but stops, and the LED shows code 12 (blower on after power up).
|
Blower On After Power Up | View Details |
| 13 |
The furnace locks out, and the LED shows code 13 (limit circuit lockout). The blower may run continuously, with the burners off.
|
Limit Circuit Lockout | View Details |
| 14 |
The furnace attempts ignition but fails, and the LED shows code 14 (ignition lockout). The furnace may retry after an hour.
|
Ignition Lockout | View Details |
| 21 |
Furnace LED shows code 21 (gas heating lockout), no heat; the blower may run for a short time then stop.
|
Gas Heating Lockout | View Details |
| 23 |
Furnace LED shows code 23 (pressure switch did not open); the inducer may run continuously even with no call for heat.
|
Pressure Switch Stuck Closed | View Details |
| 24 |
Furnace LED shows code 24 (secondary voltage fuse is open); no operation, and the thermostat appears dead.
|
Low-Voltage Fuse Open | View Details |
| 31 |
Furnace LED shows code 31 (pressure, draft safeguard, or auxiliary limit switch open). The inducer may run, but burners do not light.
|
Pressure or Draft Fault | View Details |
| 32 |
Furnace LED shows code 32 (low heat pressure switch did not close or reopened). The furnace may start, then shut down.
|
Low Heat Pressure Switch Fault | View Details |
| 33 |
Furnace LED shows code 33 (limit or flame rollout switch open). The blower may run continuously, but the burners are off.
|
Open Limit or Rollout Circuit | View Details |
| 34 |
Furnace LED shows code 34 (ignition proving failure). The ignitor glows, and burners may light briefly then go out.
|
Ignition Proving Failure | View Details |
| 41 |
Furnace LED shows code 41 (blower motor fault). The blower may not start, may run at the wrong speed, or may be noisy.
|
Indoor Blower Motor Fault | View Details |
| 42 |
Furnace LED shows code 42 (inducer motor fault). The furnace will not ignite; the inducer may not start or may start then stop.
|
Inducer Motor Fault | View Details |
| 43 |
Furnace LED shows code 43 (pressure switch calibration fault or limit circuit fault, depending on the model).
|
Pressure Switch Calibration / Limit Fault | View Details |
| 44 |
Furnace LED shows code 44 (secondary or auxiliary limit switch open). The furnace may run briefly, then shut down, while the blower continues to operate.
|
Auxiliary Limit Open | View Details |
| 45 |
Furnace LED shows code 45 (control circuit lockout). The furnace is non-responsive until power is cycled.
|
Control Circuit Lockout | View Details |
| 51 |
Furnace LED shows code 51 (gas valve relay fault). The furnace will not open the gas valve; no flame.
|
Gas Valve Relay Fault | View Details |
| 55 |
Furnace LED shows code 55 (flame sensed with gas valve off). The furnace may shut down and lock out.
|
False Flame Sense | View Details |
| – |
A burning dust smell when the furnace first starts after a long off period.
|
Dust Burn-Off | View Details |
| – |
A strong chemical or metallic burning smell during furnace operation.
|
Overheating Components / Electrical Burn | View Details |
| – |
Furnace occasionally trips the household circuit breaker.
|
Overcurrent / Electrical Short | View Details |
| – |
Furnace starts normally but shuts off when the blower comes on.
|
Blower-Induced Flame Disturbance or Voltage Drop | View Details |
| – |
Some rooms are too hot while others are too cold when the Carrier furnace runs.
|
Uneven Heating / Airflow Imbalance | View Details |
| – |
The furnace blower runs continuously even when there is no call for heat or fan from the thermostat.
|
Continuous Fan Operation | View Details |
| – |
The furnace cycles on and off frequently (every few minutes), but the house never reaches the set temperature.
|
Thermostat or Sizing-Related Short Cycling | View Details |
| – |
The furnace ignites but the flame appears mostly yellow or orange and may produce soot.
|
Improper Combustion / Yellow Flame | View Details |
| – |
The furnace makes a loud banging or booming noise at startup when the burners ignite.
|
Delayed Ignition / Burner Flashback | View Details |
| – |
The furnace produces a high-pitched whine or screeching noise during operation.
|
Blower or Inducer Mechanical Noise | View Details |
| – |
The furnace runs but produces no warm air; the blower operates, but the supply air is cool or only slightly warm.
|
Burners Not Firing / No Heat Output | View Details |
| – |
The furnace runs but the blower airflow is weak from the registers.
|
Reduced Airflow | View Details |
| – |
The furnace short cycles: burners ignite and run for 30–90 seconds, then shut off, restarting frequently.
|
Short Cycling Due to Overheating or Flame Loss | View Details |
| – |
The furnace starts, runs for a while, then shuts off and will not restart for an hour or more.
|
Soft Lockout Due to Repeated Faults | View Details |
| – |
The furnace vibrates excessively or rattles the ductwork when running.
|
Excessive Vibration / Loose Components | View Details |
| – |
The furnace will not start at all; no inducer, no blower, and no LED lights on the control board.
|
No Power to Furnace | View Details |
| – |
Thermostat calls for heat but Carrier furnace does not respond; LED shows normal idle, no fault codes.
|
No Call for Heat Reaching Furnace | View Details |
| – |
Water is dripping from the metal vent pipe on a standard-efficiency (metal vented) Carrier furnace.
|
Flue Condensation | View Details |
| – |
Water is leaking around the base of a high-efficiency (PVC vented) Carrier furnace.
|
Condensate Leak | View Details |
No matching codes found
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