Carrier Error Codes & Diagnostic Codes

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

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

Carrier error codes by equipment type

Carrier Air Conditioner error codes

Code	Meaning
16	Lost communication with user interface
25	Invalid model plug / inverter size
31	High pressure switch open
32	Low pressure trip
33	Lost inverter communication
45	Outdoor control board failure
46	Brownout
47	No 230 V at unit
48	Lost inverter communication - lockout
49	Compressor over current
53	Outdoor air temperature sensor fault
54	Suction temperature sensor fault
55	Outdoor coil temperature sensor fault
56	OAT / coil thermistor out of range
57	Suction pressure transducer fault
59	Discharge temperature high (event)
61	Fan inverter fault
63	Fan inverter current fault
65	DC bus voltage low - speed limiting
66	Outdoor fan dropped out
67	Stator heater fault
68	10-minute stage 2 warm-up delay
69	Inverter / compressor internal fault
71	Compressor dropped out
72	Suction over temperature (event)
73	Contactor shorted
74	Discharge temperature lockout
75	Maximum power mode - temperature
76	Fan inverter lockout
77	Maximum power mode - compressor current
79	Compressor / inverter fault (failed start)
81	Low stage thermal lockout
82	Suction over temperature lockout
83	Low pressure lockout (4 hours)
84	High pressure lockout (4 hours)
86	Fan inverter current lockout
88	Compressor / inverter lockout
91	Inverter DC over voltage (event)
92	Inverter DC under voltage (event)
95	Compressor over current lockout
96	DC under voltage lockout
97	DC over voltage lockout
98	High torque event
99	High torque lockout

Carrier Furnace error codes

Code	Meaning
10.1	L1 polarity fault
11	No previous code
12	Blower on after power-up (normal)
12.1	W (heat call) on at power up
13	Limit circuit lockout
13.1	Limit lockout - main limit open over 3 minutes
14	Ignition lockout
14.1	Ignition lockout after 4 tries
14.2	Lockout - flame lost 3 times after 70 s of heating
14.3	Lockout - 7 flame-loss events in one heat call
15	Blower motor lockout
21	Gas heating lockout
21.1	24 VAC on gas valve when it should be off
22	Abnormal flame-proving signal
22.1	False flame
23	Pressure switch did not open
23.1	Main pressure switch stuck closed
23.2	Secondary pressure switch stuck closed
24	Secondary (24 V) fuse open
24.1	Fuse fault (24 V)
25	Invalid model selection or setup error
25.1	No program in control
25.2	Corrupted program file
25.3	Twinned furnaces not identical
25.4	Main program invalid, running on backup
25.5	Installer settings corrupted
25.6	Wrong program for this control
25.7	Non-condensing program in condensing furnace
27.1	Super plug program missing or corrupted
27.2	Super plug program missing or corrupted
27.3	Super plug program missing or corrupted
31	High-heat pressure switch or relay did not close or reopened
31.2	Secondary pressure switch (HPS) open
31.3	Secondary pressure switch lockout
32	Low-heat pressure switch did not close or reopened
32.1	Main pressure switch (LPS) open
33	Limit circuit fault
33.1	Main limit circuit switch open
34	Ignition proving failure
34.1	Ignition fault during ignition trials
34.2	Flame lost before blower on-delay
34.3	Flame lost after blower on-delay
43	Low-heat pressure switch open while high-heat switch closed
45	Control circuitry lockout
45.1	Control failure - flame circuit / memory / sequence
45.2	Control failure - gas valve relay will not close
45.3	Control failure - EEPROM memory
46.1	Momentary loss of power
LED OFF	No amber LED - no power to control
Rapid Flash	Reversed 115-V polarity (or twinning phasing)

Carrier Heat Pump error codes

Code	Meaning
16	Lost communication with user interface
25	Invalid model plug / inverter size
31	High pressure switch open
32	Low pressure trip
33	Lost inverter communication
45	Outdoor control board failure
46	Brownout
47	No 230 V at unit
48	Lost inverter communication - lockout
49	Compressor over current
53	Outdoor air temperature sensor fault
54	Suction temperature sensor fault
55	Outdoor coil temperature sensor fault
56	OAT / coil thermistor out of range
57	Suction pressure transducer fault
59	Discharge temperature high (event)
61	Fan inverter fault
63	Fan inverter current fault
65	DC bus voltage low - speed limiting
66	Outdoor fan dropped out
67	Stator heater fault
68	10-minute stage 2 warm-up delay
69	Inverter / compressor internal fault
71	Compressor dropped out
72	Suction over temperature (event)
73	Contactor shorted
74	Discharge temperature lockout
75	Maximum power mode - temperature
76	Fan inverter lockout
77	Maximum power mode - compressor current
79	Compressor / inverter fault (failed start)
81	Low stage thermal lockout
82	Suction over temperature lockout
83	Low pressure lockout (4 hours)
84	High pressure lockout (4 hours)
86	Fan inverter current lockout
88	Compressor / inverter lockout
91	Inverter DC over voltage (event)
92	Inverter DC under voltage (event)
95	Compressor over current lockout
96	DC under voltage lockout
97	DC over voltage lockout
98	High torque event
99	High torque lockout

Find codes by Carrier 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.

Carrier error codes by equipment type

Carrier Air Conditioner error codes

Carrier Furnace error codes

Carrier Heat Pump error codes

Find codes by Carrier model

Carrier 2-stage 24ANB/25HNB

Carrier Infinity 19VS 24VNA9

Carrier Infinity 18VS 25VNA8

58SB0A/58SB1A

59MN7C

59SC6A

59TP6A

Payne PG96VTA

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