Bryant Furnace Code 10.1
Hard lockoutShown as: Rapid, continuous flashing with no pause; display reads 10.1
L1 polarity fault. The polarity of the incoming 115 V power is reversed, so the control cannot prove flame and the furnace will not run.
Manual wording: “10.1 L1 POLARITY FAULT Rapid flash LED”
Documented for: 926TC, 912SE
Likely causes, most common first
- Line voltage hot and neutral reversed at a junction box, outlet or the furnace
- On twinned furnaces, incorrect low-voltage (24 V) transformer phasing
When to call a technician
Correcting reversed 115 V polarity means working inside live junction boxes. Call a licensed HVAC technician or electrician.
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