Bryant Furnace Code 25.4
WarningShown as: Major code 25 flashed on the LED (2 short, 5 long); 25.4 on the display
Main program invalid - the control is running on its backup program. The furnace still operates normally, but the control should be reprogrammed.
Manual wording: “25.4 MAIN PROGRAM INVALID , using backup program to operate. Reprogram control to correct issue. Control still operates normally.”
Documented for: 926TC, 912SE
Likely causes, most common first
- Main program in the control became invalid
What you can safely check yourself
- Nothing urgent - the furnace still runs, but mention this code the next time a technician visits
When to call a technician
Have the dealer reprogram the control at the next service visit.
A Bryant furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Installation, Start-up, Operating and Service and Maintenance Instructions - 926TC (Bryant Heating & Cooling Systems, 926TC Preferred Series two-stage, variable-speed ECM multipoise condensing gas furnace) · checked 2026-08-25
- Installation, Start-up, Operating and Service and Maintenance Instructions - 912SE (Bryant Heating & Cooling Systems, 912SE Legacy Line 92% single-stage condensing gas furnace) · checked 2026-08-25