Carrier and Bryant 45 Error Code: Control circuitry lockout
Updated October 2026 · Sourced from Carrier and Bryant documentation
Carrier and Bryant 45 means different things on different series:
- Carrier 59SC5A single-stage 4-way multipoise condensing gas furnace (Series 1 and 2): The control locked out and auto-resets after one hour. The label gives a gas valve relay stuck open, a flame sense circuit failure or a software check error as causes, and says to reset power and replace the control if the code repeats.
- Bryant 926TC two-stage variable-speed ECM multipoise condensing gas furnace: The control reports an internal control error (45.1), GVR relay not closing (45.2), micro EEPROM error (45.3) or micro loss of communication (45.4). The label says to cycle power and replace the control if code 45 repeats.
Is it safe to keep running? No. Turn it off and get it checked. Call a licensed technician if the code repeats after the power reset. The control board needs to be replaced by a pro.
45 at a glance
| Code / how it shows | Meaning | Applies to |
|---|---|---|
| 45 Status LED flashes: first digit is short flashes, second digit is long flashes | Control circuitry lockout | Carrier 59SC5A single-stage 4-way multipoise condensing gas furnace (Series 1 and 2) |
| 45 Also: 45.1, 45.2, 45.3, 45.4 Status LED flashes: first digit is short flashes, second digit is long flashes; display shows 45.1 to 45.4 | Control board fault | Bryant 926TC two-stage variable-speed ECM multipoise condensing gas furnace |
Check this first
Only steps a homeowner can do safely. Do not open electrical panels or the burner area.
- Turn the furnace power off at the switch or breaker, wait one minute, then turn it back on to see whether the code returns.
🛑 Stop and call a licensed pro if
- Call a licensed technician if the code repeats after the power reset. The control board needs to be replaced by a pro.
- You smell gas. Leave the house, do not touch switches, and call your gas utility from outside.
- Flame rollout, limit or pressure switch codes that come back after one reset.
- Anything involving the control board, gas valve, flame sensor, igniter or venting.
- A carbon monoxide alarm sounds. Get everyone outside and call 911 or the fire department.
Safe first steps for any Carrier and Bryant code
- Count the LED flashes through the blower door window before you switch anything off. Cutting power can clear the code.
- Replace or clean the furnace air filter.
- Check the thermostat: correct mode, set above room temperature, and fresh batteries.
- Make sure the furnace power switch and breaker are on. If the furnace has locked out, turning the power off and back on once restarts it.
- Make sure the gas valve is in the ON position, following the lighting instructions on the furnace label only.
- On high-efficiency furnaces, look at the outside vent and intake pipes for snow, ice, leaves or nests (look only, do not take pipes apart).
Sources: Carrier 59SC5A Installation, Start-up, Operating and Service and Maintenance Instructions, Fig. 62 Service Label, p.67; Bryant 926TC Installation, Start-up, Operating and Service and Maintenance Instructions, Service Label (Status Code Table), p.56. Codes are series-specific, so your unit's own manual is the final word. Reviewed October 2026.
Shaun Cain · Certified HVAC & Refrigeration Technician · Ask an HVAC technician