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Carrier 58SB0A / 58SB1A Furnace Codes

Applies to: Carrier 58SB0A / 58SB1A (single-stage, non-condensing). LED on the furnace control, two-digit status codes.

Similar two-digit status codes are used on many Carrier, Bryant and Payne furnaces, but titles and causes vary by model. Check the service label on the blower door.

CodeMeaningWhat to check
11No previous code.
12Blower on after power up (normal).Blower runs for 90 seconds if the unit is powered up during a call for heat, or when R-W opens during the blower on-delay.
13Limit circuit lockout.A limit, draft safeguard, flame rollout or blocked vent switch stayed open longer than 3 minutes. Auto-resets after 3 hours. See code 33. How to fix →
14Ignition lockout.Failed to ignite and prove flame in 4 attempts. Auto-resets after 3 hours. See code 34. How to fix →
21Gas heating lockout.Turn off power and wait 5 minutes to retry. Stuck-closed gas valve relay on the control, or a miswire or short to the gas valve wire.
22Abnormal flame-proving signal.Flame is proved while the gas valve is de-energized; the inducer runs until it clears. Stuck-open or leaky gas valve. How to fix →
23Pressure switch did not open.Obstructed pressure tube, or pressure switch stuck closed. How to fix →
24Secondary voltage fuse is open.Short in the 24 V wiring, including thermostat leads. Disconnect thermostat leads to isolate it. How to fix →
31Pressure switch did not close or reopened.Vent sizing or restriction, low inducer voltage, combustion air, pressure tubing, inducer motor, pressure switch, wind. Open more than 5 minutes: inducer shuts off for 15 minutes before retrying. How to fix →
33Limit circuit fault.Limit, draft safeguard, flame rollout or blocked vent switch is open. Dirty filter or restricted ducts, loose blower wheel, blower motor or capacitor, combustion air, restricted vent. Rollout and blocked vent switches are manual reset. How to fix →
34Ignition proving failure.Flame not sensed during the trial; the control tries 3 more times before code 14. Gas valve and manual shut-off, burner ground wire, flame sensor not grounded. How to fix →
45Control circuitry lockout.Flame circuit failure, gas valve relay stuck open, or a software check error. Auto-resets after 1 hour. Reset power; replace the control if the code repeats.

How to read the codes

Codes point to a circuit, not a part. Test before replacing anything, and never jumper a limit, rollout or pressure switch to keep a furnace running. Gas and line-voltage work is for trained technicians.

Source: Carrier 58SB0A/58SB1A Installation, Start-Up, Operating and Service and Maintenance Instructions, Fig. 51 Troubleshooting Guide (p. 38). The "meaning" column follows the manufacturer's wording; "what to check" is our field summary. Always go by the label on the furnace you're working on.

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