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Carrier gas furnace error codes

Complete list of 93 checked codes for Carrier gas furnaces, with what each code means and whether you can fix it yourself.

Reference sheet from https://faultcodeindex.com/carrier/gas-furnace/ (checked against Carrier manuals).

93 codes
Code Meaning What you can do
11 No previous fault stored You can often fix it
13 Limit circuit lockout (depends on model) Safe checks first, then a pro
14 Ignition lockout after repeated failed lighting attempts Safe checks first, then a pro
15 Blower motor lockout Call a pro
21 Gas heating lockout, fault in the gas valve circuit Safe checks first, then a pro
22 Flame sensed while the gas valve is off Safe checks first, then a pro
23 Flue or venting fault (depends on model) Call a pro
24 24-volt fuse on the control has blown Call a pro
25 Model plug missing or wrong, or a setup switch error Call a pro
26 Burner thermal switch open Call a pro
31 Flue or venting fault (depends on model) Safe checks first, then a pro
32 Low or low-heat pressure switch did not close, or opened again Safe checks first, then a pro
33 Limit circuit fault, a limit or rollout switch is open Safe checks first, then a pro
34 Flame not proved during ignition Safe checks first, then a pro
35 Modulating gas valve not communicating Call a pro
41 Blower motor fault, speed or communication lost Call a pro
42 Inducer motor fault Safe checks first, then a pro
43 Lower pressure switch open while a higher one is closed Call a pro
45 Control circuitry lockout Call a pro
10.1 Line voltage polarity reversed Call a pro
10.2 Refrigerant leak detected, dissipation active Call a pro
13.1 Limit circuit lockout, a limit or rollout switch stayed open Safe checks first, then a pro
14.1 Ignition lockout after repeated failed lighting attempts Safe checks first, then a pro
14.2 Flame lost 3 times after 70 seconds of heating Safe checks first, then a pro
14.3 Lockout after 7 flame losses in one heat request Safe checks first, then a pro
14.4 Lockout after repeated pressure switch openings Safe checks first, then a pro
15.1 Blower lockout, no blower speed signal Call a pro
15.2 Blower lockout, blower never reached 500 rpm Call a pro
17.1 Lost communication with the Bluetooth module Call a pro
19.1 Lost InteliSense communication with the thermostat Call a pro
21.1 24 volts sensed at the gas valve when there should be none Safe checks first, then a pro
22.1 Flame proved while the gas valve is off Safe checks first, then a pro
23.1 Flue or venting fault (depends on model) Call a pro
23.2 Secondary pressure switch stuck closed Call a pro
23.3 Pressure transducer senses over-pressure Call a pro
23.4 Low pressure switch stuck closed Call a pro
23.5 High pressure switch stuck closed Call a pro
23.6 Medium pressure switch stuck closed Call a pro
24.1 Fuse fault, short in the 24-volt wiring Call a pro
25.1 Control has no program loaded Call a pro
25.2 Control program file is corrupted Call a pro
25.3 Twinned furnaces are not identical Call a pro
25.4 Main program invalid, running on the backup program Call a pro
25.5 Installer settings are corrupted Call a pro
25.6 Wrong program loaded for this control Call a pro
25.7 Non-condensing program in a condensing furnace Call a pro
26.1 Burner thermal switch open, permanent lockout Call a pro
26.2 Burner thermal switch open, permanent lockout Call a pro
27.1 Program in super plug is missing or corrupted Call a pro
27.2 Program in super plug is missing or corrupted Call a pro
27.3 Program in super plug is missing or corrupted Call a pro
31.1 Flue or venting fault (depends on model) Depends on your model
31.2 Flue or venting fault (depends on model) Depends on your model
31.3 Secondary pressure switch lockout after 3 failed trials Safe checks first, then a pro
31.4 Loss of pressure before the blower started Safe checks first, then a pro
31.5 Loss of pressure after the blower started Safe checks first, then a pro
31.6 High pressure switch open Safe checks first, then a pro
31.7 High heat only, high switch failed to close in time Safe checks first, then a pro
32.1 Main pressure switch (LPS) open Safe checks first, then a pro
32.2 Low pressure switch open Safe checks first, then a pro
33.1 Limit circuit switch open, blower running to cool the furnace Safe checks first, then a pro
33.2 High heat only for the current cycle Safe checks first, then a pro
34.1 Ignition fault, burners did not light in 4 trials Safe checks first, then a pro
34.2 Flame lost before the heating blower started Safe checks first, then a pro
34.3 Flame lost after the heating blower started Safe checks first, then a pro
34.4 Flame lost at reduced inducer pressure or in Self Healing mode Safe checks first, then a pro
34.5 Low heat flame lost before the blower started Safe checks first, then a pro
34.6 Low heat flame lost after the blower started Safe checks first, then a pro
34.7 High heat flame lost before the blower started Safe checks first, then a pro
34.8 High heat flame lost after the blower started Safe checks first, then a pro
35.1 Modulating gas valve not communicating Call a pro
41.1 No blower speed at start-up Call a pro
41.2 Blower speed lost while running Call a pro
41.3 Blower not reaching 500 rpm Call a pro
42.1 No inducer speed at start-up Call a pro
42.2 Inducer speed lost while running Call a pro
42.3 Inducer over its speed limit Call a pro
43.1 High switch closed before the low switch Call a pro
45.1 Internal control fault Call a pro
45.2 Gas valve relay will not close Call a pro
45.3 Control memory (EEPROM) fault Call a pro
45.4 Microprocessor communication lost Call a pro
46.1 Momentary loss of power Call a pro
51.1 Outdoor air sensor open Call a pro
51.2 Outdoor air sensor shorted Call a pro
52.1 Supply air sensor open Call a pro
52.2 Supply air sensor shorted Call a pro
53.1 Return air sensor open Call a pro
53.2 Return air sensor shorted Call a pro
btL Firmware failed to load Call a pro
amber light off No power to the furnace control You can often fix it
amber light flashing rapidly Line voltage polarity reversed or the furnace is not grounded Call a pro
steady amber light Normal, the control has power and no fault to show You can often fix it

Model ranges