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Carrier gas furnace code 10.1: Line voltage polarity reversed

Gas furnace, Canada and United States

The 115-volt supply to the furnace is wired with the wrong polarity. The status light flashes rapidly without a pause and the furnace will not run.

This needs a licensed gas technician. There is nothing safe to check yourself. Leave the covers on and book a professional.

What causes it

  1. The line and neutral wires of the 115-volt supply are reversed at the furnace.

    Book a licensed gas technician

  2. On two furnaces installed as a twinned pair, the 24-volt transformers are not phased correctly.

    Book a licensed gas technician

How to read this code on your unit

The three-digit display sits on the furnace control behind the blower door. Through the sight glass in the door you see only the status light, which flashes the first two digits of the code. Count the short flashes for the first digit, then the long flashes for the second, so 3 short flashes followed by 3 long flashes is a 33.x code. Write down what you see before you open the door or switch the furnace off. The full code with its third digit shows on the control display only with the door removed and the door switch closed, which is a job for a technician. A technician can also look back at the last 7 faults in the FLt menu. Stored codes are erased by themselves after 72 hours of powered operation after the last fault, and the display shows non when no fault is stored.

Booking a licensed gas technician

Book a licensed gas technicianlicensed gas technician

  1. Turn the unit off and leave the covers on. Gas components must only be serviced by a licensed technician.
  2. Note the code, how often it appears, and the model and serial numbers from the rating label.
  3. Book a licensed gas technician and give them those details.

Models that show this code

164 models in 16 ranges
RangeModels
58SB0B/58SB1B58SB0B045M14-12, 58SB0B045M17-14, 58SB0B070M14-12, 58SB0B070M17-12, 58SB0B070M17-16, 58SB0B070M21-16, 58SB0B090M17-14, 58SB0B090M21-16, 58SB0B090M21-20, 58SB0B090M24-20, 58SB0B110M21-20, 58SB0B110M24-20, 58SB0B135M24-20, 58SB0B155M24-20, 58SB1B045M14-12, 58SB1B045M17-14, 58SB1B070M14-12, 58SB1B070M17-12, 58SB1B070M17-16, 58SB1B070M21-16, 58SB1B090M17-14, 58SB1B090M21-16, 58SB1B090M21-20, 58SB1B090M24-20, 58SB1B110M21-20, 58SB1B110M24-20, 58SB1B135M24-20, 58SB1B155M24-20
58SC0B/58SC1B58SC0B045M14-12, 58SC0B045M17-14, 58SC0B070M14-12, 58SC0B070M17-12, 58SC0B070M17-16, 58SC0B070M21-16, 58SC0B090M17-14, 58SC0B090M21-16, 58SC0B090M21-20, 58SC0B110M21-20, 58SC0B110M24-20, 58SC0B135M24-20, 58SC1B045M14-12, 58SC1B045M17-14, 58SC1B070M14-12, 58SC1B070M17-12, 58SC1B070M17-16, 58SC1B070M21-16, 58SC1B090M17-14, 58SC1B090M21-16, 58SC1B090M21-20, 58SC1B110M21-20, 58SC1B110M24-20, 58SC1B135M24-20
58SP0B/58SP1B58SP0B045V14-12, 58SP0B070V14-12, 58SP0B070V17-16, 58SP0B090V17-16, 58SP0B090V21-20, 58SP0B110V21-22, 58SP0B135V24-22, 58SP1B045V14-12, 58SP1B070V14-12, 58SP1B070V17-16, 58SP1B090V17-16, 58SP1B090V21-20, 58SP1B110V21-22, 58SP1B135V24-22
58TN0B/58TN1B58TN0B045C17-12, 58TN0B070C14-12, 58TN0B070C17-16, 58TN0B070C21-20, 58TN0B090C17-16, 58TN0B090C21-20, 58TN0B110C21-20, 58TN0B135C24-22, 58TN1B045C17-12, 58TN1B070C14-12, 58TN1B070C17-16, 58TN1B070C21-20, 58TN1B090C17-16, 58TN1B090C21-20, 58TN1B110C21-20, 58TN1B135C24-22
58TP0B/58TP1B58TP0B045V14-12, 58TP0B070V14-12, 58TP0B070V17-16, 58TP0B090V17-16, 58TP0B090V21-20, 58TP0B110V21-22, 58TP0B135V24-22, 58TP1B045V14-12, 58TP1B070V14-12, 58TP1B070V17-16, 58TP1B090V17-16, 58TP1B090V21-20, 58TP1B110V21-22, 58TP1B135V24-22
59SC2E59SC2E040M14-12, 59SC2E040M17-12, 59SC2E060M14-12, 59SC2E060M17-14, 59SC2E080M17-16, 59SC2E080M21-20, 59SC2E100M21-20, 59SC2E100M21-22, 59SC2E120M24-20
59SC6A59SC6A026M14-10, 59SC6A040M14-10, 59SC6A040M17-12, 59SC6A060M14-12, 59SC6A060M17-16, 59SC6A080M17-16, 59SC6A080M21-20, 59SC6A100M21-20, 59SC6A100M21-22, 59SC6A120M24-22, 59SC6A140M24-22
59TN6C59TN6C040C14-10, 59TN6C060C17-14, 59TN6C080C17-14, 59TN6C080C21-20, 59TN6C100C21-22, 59TN6C120C24-22
59TN7A59TN7A060C17-16, 59TN7A080C17-16, 59TN7A080C21-20, 59TN7A100C21-22, 59TN7A120C24-22
59TP6C59TP6C040V14-10, 59TP6C040V17-12, 59TP6C060V14-12, 59TP6C060V17-16, 59TP6C080V17-16, 59TP6C080V21-20, 59TP6C100V21-20, 59TP6C100V21-22, 59TP6C120V24-22
59TP7A59TP7A060V17-16, 59TP7A080V17-16, 59TP7A080V21-20, 59TP7A100V21-20, 59TP7A100V21-22, 59TP7A120V24-22
58CU0B58CU0B040C17-12, 58CU0B060C17-16, 58CU0B080C21-20, 58CU0B100C21-20
58SU0B58SU0B040M17-12, 58SU0B060M17-16, 58SU0B080M21-20, 58SU0B100M21-20
59CU5B59CU5B060C17-16, 59CU5B080C21-20, 59CU5B100C21-22
59SU5B59SU5B040M17-12, 59SU5B060M17-16, 59SU5B080M21-20, 59SU5B100M21-20, 59SU5B100M21-22
59MN7C59MN7C060C17-14, 59MN7C060C21-20, 59MN7C080C17-14, 59MN7C080C21-20, 59MN7C100C21-22, 59MN7C120C24-22

Where this comes from

Checked against the manufacturer's manual on 11 October 2026.

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Other Carrier gas furnace codes

Code Meaning What you can do
24 24-volt fuse on the control has blown Call 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
10.2 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
24.1 Fuse fault, short in the 24-volt wiring Call a pro
amber light flashing rapidly Line voltage polarity reversed or the furnace is not grounded Call a pro

See all electrical fault codes on gas furnaces across brands.