Carrier Furnace Error Codes

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

50 Carrier Furnace error codes and diagnostic codes, with causes and troubleshooting steps for each. Select a code, or find your model below.

Homeowner with a furnace problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

Carrier Furnace error codes list

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

Find codes by Carrier model

Furnace troubleshooting guides

Blowing cold air All brands · Furnace
No heat All brands · Furnace
Short cycling All brands · Furnace
Burners will not light or stay lit - Carrier 58SB0A/58SB1A Carrier · Furnace
Furnace not responding to thermostat - Carrier 58SB0A/58SB1A Carrier · Furnace

Carrier Furnace specs and setup data

Minimum clearances to combustibles Carrier · Furnace · 59TP6A
Minimum clearances to combustibles Carrier · Furnace · 59SC6A
Filter sizes by casing width Carrier · Furnace · 58SB0A/58SB1A
Filter sizes by casing width Carrier · Furnace · Payne PG96VTA
Filter sizes by casing width and filter cabinet Carrier · Furnace · 59SC6A
Filter sizes by casing width and filter cabinet Carrier · Furnace · 59TP6A

Homeowner help: Furnace Not Turning On: What to Check · Furnace Blinking Light: What the Flash Codes Mean

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 Furnace error codes list

Find codes by Carrier model

58SB0A/58SB1A

59MN7C

59SC6A

59TP6A

Payne PG96VTA

Furnace troubleshooting guides

Carrier Furnace specs and setup data

Experience an Energy-Efficient Thermostat in Ajax Today