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Carrier gas furnace code 25.5: Installer settings are corrupted

Gas furnace, Canada and United States

The installer settings are corrupted, so the control runs on its default installer settings. A technician reselects the settings or reprograms the control.

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 installer settings in the control are corrupted. A technician reselects them or reprograms the control.

    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
25 Model plug missing or wrong, or a setup switch error 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
25.6 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
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
btL Firmware failed to load Call a pro

See all configuration error codes on gas furnaces across brands.