Trane Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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1 Flash
Status LED flashes once repeatedly, furnace will not start heating cycle
Ignition Failure / Lockout
2 Flashes
Status LED flashes twice repeatedly, furnace will not run, inducer may not start
Pressure Switch Stuck Closed
3 Flashes
Status LED flashes three times repeatedly, inducer runs but burners do not light
Pressure Switch Stuck Open
4 Flashes
Status LED flashes four times repeatedly, furnace starts but shuts down shortly after ignition
Open High Limit Switch
5 Flashes
Status LED flashes five times repeatedly, furnace will not start heating cycle
Flame Sensed With Gas Valve Off (False Flame Signal)
6 Flashes
Status LED flashes six times repeatedly, furnace shuts down and may lock out
Flame Loss During Run
7 Flashes
Status LED flashes seven times repeatedly, furnace will not start heating cycle
Gas Valve Circuit Fault
8 Flashes
Status LED flashes eight times repeatedly, furnace may start but shuts down quickly
Low Flame Sense Signal
9 Flashes
Status LED flashes nine times repeatedly, furnace will not operate
Reversed Line Polarity or Ground Fault
Blinking Off (No LED)
No LED light, furnace completely dead
No Power to Furnace
Continuous Fast Flash
Status LED flashes rapidly without pause, furnace does not respond to thermostat
Incorrect 24V Phase / Low Voltage Polarity
Err 1
Trane communicating furnace control displays 'Err 1' on the ComfortLink II or communicating thermostat
Communication Error Between Thermostat and Furnace
Err 2
Trane communicating thermostat shows 'Err 2', furnace may not respond
Outdoor Unit Communication Fault (in dual fuel or integrated systems)
Err 3
Trane communicating thermostat shows 'Err 3', furnace may shut down
Indoor Temperature Sensor Fault
Err 4
Trane communicating thermostat shows 'Err 4', furnace may not operate correctly
Outdoor Temperature Sensor Fault (for dual fuel or outdoor sensor-equipped systems)
Err 5
Trane communicating thermostat shows 'Err 5', system may lock out certain modes
Configuration or Component Mismatch Error
HARD LOCKOUT
Control indicates hard lockout, furnace will not attempt ignition until reset
Repeated Ignition Failure Lockout
SOFT LOCKOUT
Control indicates soft lockout, furnace pauses operation for a timed period then retries
Temporary Ignition or Flame Sensing Lockout
Steady On
Status LED solid on with no flashing, furnace not responding or stuck
Normal Power / No Call or Control Board Locked
Symptom
Burning or electrical smell when furnace runs
Overheating Components or Electrical Fault
Symptom
Furnace blower runs continuously even when thermostat is not calling for heat or fan
Blower Stuck in Continuous Operation
Symptom
Furnace blower starts but there is no warm air, burners never ignite
No Heat / Blower Only Operation
Symptom
Furnace cycles on and off with loud clicking from control area, but burners do not stay lit
Control Board or Relay Malfunction
Symptom
Furnace emits a strong gas smell when attempting to start
Gas Leak or Incomplete Ignition
Symptom
Furnace frequently trips the household circuit breaker
Electrical Overload or Short Circuit
Symptom
Furnace ignites but produces yellow, lazy flames instead of blue
Improper Combustion
Symptom
Furnace inducer runs continuously but burners do not light
Draft Proving / Pressure Switch Problem
Symptom
Furnace makes loud banging or booming noise at startup
Delayed Ignition
Symptom
Furnace produces a high-pitched squealing noise during operation
Blower Motor or Belt Noise
Symptom
Furnace rattles or vibrates loudly when running
Cabinet or Duct Vibration
Symptom
Furnace runs but airflow from registers is weak
Low Airflow
Symptom
Furnace runs but house does not reach set temperature, long run times
Insufficient Heat Output
Symptom
Furnace short cycles, turning on and off frequently without reaching temperature
Short Cycling
Symptom
Furnace starts and runs but shuts off after a few minutes, then restarts after cooling
Overheating / High Limit Cycling
Symptom
Furnace starts but shuts down immediately when blower starts
Blower-Induced Flame Disturbance or Limit Trip
Symptom
Furnace will not start at all, no blower, no inducer, thermostat calling for heat
Complete Power Loss to Furnace
Symptom
Thermostat calls for heat but furnace inducer starts and then shuts off without ignition
Failed Ignition Sequence
Symptom
Thermostat display is blank and furnace does not run
Loss of 24V Control Power
Symptom
Water dripping from PVC vent pipe joints or around exhaust outlet
Condensate in Vent Piping
Symptom
Water leaking around the base of a high-efficiency Trane furnace
Condensate Leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| 1 Flash |
Status LED flashes once repeatedly, furnace will not start heating cycle
|
Ignition Failure / Lockout | View Details |
| 2 Flashes |
Status LED flashes twice repeatedly, furnace will not run, inducer may not start
|
Pressure Switch Stuck Closed | View Details |
| 3 Flashes |
Status LED flashes three times repeatedly, inducer runs but burners do not light
|
Pressure Switch Stuck Open | View Details |
| 4 Flashes |
Status LED flashes four times repeatedly, furnace starts but shuts down shortly after ignition
|
Open High Limit Switch | View Details |
| 5 Flashes |
Status LED flashes five times repeatedly, furnace will not start heating cycle
|
Flame Sensed With Gas Valve Off (False Flame Signal) | View Details |
| 6 Flashes |
Status LED flashes six times repeatedly, furnace shuts down and may lock out
|
Flame Loss During Run | View Details |
| 7 Flashes |
Status LED flashes seven times repeatedly, furnace will not start heating cycle
|
Gas Valve Circuit Fault | View Details |
| 8 Flashes |
Status LED flashes eight times repeatedly, furnace may start but shuts down quickly
|
Low Flame Sense Signal | View Details |
| 9 Flashes |
Status LED flashes nine times repeatedly, furnace will not operate
|
Reversed Line Polarity or Ground Fault | View Details |
| Blinking Off (No LED) |
No LED light, furnace completely dead
|
No Power to Furnace | View Details |
| Continuous Fast Flash |
Status LED flashes rapidly without pause, furnace does not respond to thermostat
|
Incorrect 24V Phase / Low Voltage Polarity | View Details |
| Err 1 |
Trane communicating furnace control displays 'Err 1' on the ComfortLink II or communicating thermostat
|
Communication Error Between Thermostat and Furnace | View Details |
| Err 2 |
Trane communicating thermostat shows 'Err 2', furnace may not respond
|
Outdoor Unit Communication Fault (in dual fuel or integrated systems) | View Details |
| Err 3 |
Trane communicating thermostat shows 'Err 3', furnace may shut down
|
Indoor Temperature Sensor Fault | View Details |
| Err 4 |
Trane communicating thermostat shows 'Err 4', furnace may not operate correctly
|
Outdoor Temperature Sensor Fault (for dual fuel or outdoor sensor-equipped systems) | View Details |
| Err 5 |
Trane communicating thermostat shows 'Err 5', system may lock out certain modes
|
Configuration or Component Mismatch Error | View Details |
| HARD LOCKOUT |
Control indicates hard lockout, furnace will not attempt ignition until reset
|
Repeated Ignition Failure Lockout | View Details |
| SOFT LOCKOUT |
Control indicates soft lockout, furnace pauses operation for a timed period then retries
|
Temporary Ignition or Flame Sensing Lockout | View Details |
| Steady On |
Status LED solid on with no flashing, furnace not responding or stuck
|
Normal Power / No Call or Control Board Locked | View Details |
| – |
Burning or electrical smell when furnace runs
|
Overheating Components or Electrical Fault | View Details |
| – |
Furnace blower runs continuously even when thermostat is not calling for heat or fan
|
Blower Stuck in Continuous Operation | View Details |
| – |
Furnace blower starts but there is no warm air, burners never ignite
|
No Heat / Blower Only Operation | View Details |
| – |
Furnace cycles on and off with loud clicking from control area, but burners do not stay lit
|
Control Board or Relay Malfunction | View Details |
| – |
Furnace emits a strong gas smell when attempting to start
|
Gas Leak or Incomplete Ignition | View Details |
| – |
Furnace frequently trips the household circuit breaker
|
Electrical Overload or Short Circuit | View Details |
| – |
Furnace ignites but produces yellow, lazy flames instead of blue
|
Improper Combustion | View Details |
| – |
Furnace inducer runs continuously but burners do not light
|
Draft Proving / Pressure Switch Problem | View Details |
| – |
Furnace makes loud banging or booming noise at startup
|
Delayed Ignition | View Details |
| – |
Furnace produces a high-pitched squealing noise during operation
|
Blower Motor or Belt Noise | View Details |
| – |
Furnace rattles or vibrates loudly when running
|
Cabinet or Duct Vibration | View Details |
| – |
Furnace runs but airflow from registers is weak
|
Low Airflow | View Details |
| – |
Furnace runs but house does not reach set temperature, long run times
|
Insufficient Heat Output | View Details |
| – |
Furnace short cycles, turning on and off frequently without reaching temperature
|
Short Cycling | View Details |
| – |
Furnace starts and runs but shuts off after a few minutes, then restarts after cooling
|
Overheating / High Limit Cycling | View Details |
| – |
Furnace starts but shuts down immediately when blower starts
|
Blower-Induced Flame Disturbance or Limit Trip | View Details |
| – |
Furnace will not start at all, no blower, no inducer, thermostat calling for heat
|
Complete Power Loss to Furnace | View Details |
| – |
Thermostat calls for heat but furnace inducer starts and then shuts off without ignition
|
Failed Ignition Sequence | View Details |
| – |
Thermostat display is blank and furnace does not run
|
Loss of 24V Control Power | View Details |
| – |
Water dripping from PVC vent pipe joints or around exhaust outlet
|
Condensate in Vent Piping | View Details |
| – |
Water leaking around the base of a high-efficiency Trane furnace
|
Condensate Leak | View Details |
No matching codes found
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