Bryant Furnace Code 34.3
Safety faultShown as: Major code 34 on the LED (3 short, 4 long); 34.3 on the display
After successful ignition (flame proven), flame was lost after the heating blower on-delay.
Manual wording: “34.3 AFTER SUCCESSFUL IGNITION flame loss after heating blower on delay”
Documented for: 926TC, 912SE
Likely causes, most common first
- Oxide buildup on the flame sensor
- Low inlet gas pressure
- Poor control ground continuity
- Airflow disturbing the flame
What you can safely check yourself
- Check that the air filter is clean and supply/return vents are open
When to call a technician
Losing flame once the blower comes on often points at gas pressure or flame sensing. Have a technician measure flame current and manifold pressure.
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