Trane Error Codes & Diagnostic Codes

Updated October 13, 2026 · by Aurora Star Tech Inc.

Trane error codes and diagnostic codes: look up a code to see what it means, the likely causes and the steps to fix it.

Trane error codes by equipment type

Trane Air Conditioner error codes

Code	Meaning
2nd digit 1	MOC fault (A1000AA board)
2nd digit 2	MOC communication fault (A1000AA board)
2nd digit 3	Compressor internal protection (IOL/OLP) (A1000AA board)
2nd digit 4	Compressor over-current protection (A1000AA board)
2nd digit 5	Outdoor fan over-current protection (A1000AA board)
2nd digit 6	High preheat IPM temperature (A1000AA board)
2nd digit 7	High coil temperature protection (A1000AA board)
2nd digit 8	High discharge temperature protection (A1000AA board)
2nd digit 9	High drive compressor IPM temperature (A1000AA board)
2nd digit A	Outdoor ambient sensor fault (A1000AA board)
2nd digit b	AOC jumper pin engaged (A1000AA board)
2nd digit C	Coil temperature sensor fault (A1000AA board)
2nd digit d	Discharge temperature sensor fault (A1000AA board)
2nd digit E	High drive PFC temperature protection (A1000AA board)
2nd digit F	High drive fan IPM temperature protection (A1000AA board)
2nd digit P	Pressure protection (high or low) (A1000AA board)
d5	De-rate: drive AC input over-current
d6	De-rate: high drive IPM temperature
d7	De-rate: high drive PFC temperature
d8	De-rate: high coil temperature
dC	De-rate: compressor over-current
dd	De-rate: high discharge temperature
dF	De-rate: outdoor fan over-current
E0	Personality module error
E1	Configuration error
E2	AOC software / configuration mismatch
F0	AOC-MOC communication fault
F1	Compressor start-up fault
F2	Compressor over-current
F3	Compressor control fault
F4	Outdoor fan control fault
F5	AC over-current fault
F6	Drive high temperature fault
F7	AC input voltage low
F8	DC output voltage fault
F9	Drive (MOC) internal fault
FA	Outdoor ambient sensor fault
FC	Coil temperature sensor fault
Fd	Discharge temperature sensor fault
H5	Hard lock: drive AC input over-current
H6	Hard lock: high drive IPM temperature
H7	Hard lock: high drive PFC temperature
H8	Hard lock: high coil temperature
HC	Hard lock: compressor over-current
Hd	Hard lock: high discharge temperature
HF	Hard lock: outdoor fan over-current
HH	Hard lock: high pressure (HPCO / DTC)
HL	Hard lock: low pressure (LPCO)
L5	Lockout: drive AC input over-current
L6	Lockout: high drive IPM temperature
L7	Lockout: high drive PFC temperature
L8	Lockout: high coil temperature
LC	Lockout: compressor over-current
Ld	Lockout: high discharge temperature
LF	Lockout: outdoor fan over-current
LH	Lockout: high pressure (HPCO / DTC)
LL	Lockout: low pressure (LPCO)

Trane Air Handler error codes

Code	Meaning
E01	Blower control (IMBC) internal failure
E6.1	120 V polarity reversed
E6.2	Ground not detected
E12	Control fuse open
E13	Blower HP / OEM ID mismatch
E14	No personality module and local copy bad
E15	Unit data file corrupt in module and control
E17	Blower motor not responding
E18	Blower communication failure on the control side

Trane Furnace error codes

Code	Meaning
E01	Furnace control internal failure
E04	Open limit (main limit, rollout or reverse airflow)
E05	Flame sensed when no flame should be present
E08	Low flame signal (still running)
E2.1	Ignition retries exceeded - flame never proven (1 hour lockout)
E2.2	Flame recycles exceeded - flame lost after lighting (1 hour lockout)
E2.3	1st stage gas valve not powered when it should be (10 times)
E3.1	1st stage pressure switch (PS1) closed when it should be open
E3.2	1st stage pressure switch (PS1) open when it should be closed
E3.3	2nd stage pressure switch (PS2) closed when it should be open
E3.4	2nd stage pressure switch (PS2) open when it should be closed
E4.0	Main high limit open
E4.1	Reverse airflow limit open
E4.2	Flame rollout switch open
E6.1	120 V polarity reversed
E6.2	Ground not detected
E6.3	Igniter open or igniter relay fault
E7.1	1st stage gas valve (MVL) powered with no call
E7.2	Redundant relay (HLO output) on with no call
E11	Gas valve relay / valve circuit fault
E12	Control fuse open
E13	Blower motor size / OEM ID mismatch
E14	Configuration file error
E17	Blower motor communication error
E23	Menu data not received by combustion micro (CCM)
E24	Internal communication error between ACM and CCM
E25	Orientation sensor out of range
E26	Return static pressure sensor out of range or not connected
E27	Return air thermistor out of range or not connected
E28	Supply air thermistor out of range or not connected

Trane Heat Pump error codes

Code	Meaning
2nd digit 1	MOC fault (A1000AA board)
2nd digit 2	MOC communication fault (A1000AA board)
2nd digit 3	Compressor internal protection (IOL/OLP) (A1000AA board)
2nd digit 4	Compressor over-current protection (A1000AA board)
2nd digit 5	Outdoor fan over-current protection (A1000AA board)
2nd digit 6	High preheat IPM temperature (A1000AA board)
2nd digit 7	High coil temperature protection (A1000AA board)
2nd digit 8	High discharge temperature protection (A1000AA board)
2nd digit 9	High drive compressor IPM temperature (A1000AA board)
2nd digit A	Outdoor ambient sensor fault (A1000AA board)
2nd digit b	AOC jumper pin engaged (A1000AA board)
2nd digit C	Coil temperature sensor fault (A1000AA board)
2nd digit d	Discharge temperature sensor fault (A1000AA board)
2nd digit E	High drive PFC temperature protection (A1000AA board)
2nd digit F	High drive fan IPM temperature protection (A1000AA board)
2nd digit P	Pressure protection (high or low) (A1000AA board)
d5	De-rate: drive AC input over-current
d6	De-rate: high drive IPM temperature
d7	De-rate: high drive PFC temperature
d8	De-rate: high coil temperature
dC	De-rate: compressor over-current
dd	De-rate: high discharge temperature
dF	De-rate: outdoor fan over-current
E0	Personality module error
E1	Configuration error
E2	AOC software / configuration mismatch
F0	AOC-MOC communication fault
F1	Compressor start-up fault
F2	Compressor over-current
F3	Compressor control fault
F4	Outdoor fan control fault
F5	AC over-current fault
F6	Drive high temperature fault
F7	AC input voltage low
F8	DC output voltage fault
F9	Drive (MOC) internal fault
FA	Outdoor ambient sensor fault
FC	Coil temperature sensor fault
Fd	Discharge temperature sensor fault
Fr	No 24 VAC R signal at outdoor control (heat pump)
H5	Hard lock: drive AC input over-current
H6	Hard lock: high drive IPM temperature
H7	Hard lock: high drive PFC temperature
H8	Hard lock: high coil temperature
HC	Hard lock: compressor over-current
Hd	Hard lock: high discharge temperature
HF	Hard lock: outdoor fan over-current
HH	Hard lock: high pressure (HPCO / DTC)
HL	Hard lock: low pressure (LPCO)
L5	Lockout: drive AC input over-current
L6	Lockout: high drive IPM temperature
L7	Lockout: high drive PFC temperature
L8	Lockout: high coil temperature
LC	Lockout: compressor over-current
Ld	Lockout: high discharge temperature
LF	Lockout: outdoor fan over-current
LH	Lockout: high pressure (HPCO / DTC)
LL	Lockout: low pressure (LPCO)

Find codes by Trane model

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.

Trane error codes by equipment type

Trane Air Conditioner error codes

Trane Air Handler error codes

Trane Furnace error codes

Trane Heat Pump error codes

Find codes by Trane model

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