Bryant Furnace Code 31.3
Soft lockoutShown as: Major code 31 on the LED (3 short, 1 long); 31.3 on the display
Secondary pressure switch lockout - the secondary (high-heat) pressure switch failed to close after three trials.
Manual wording: “31 3 Secondary PS Lockout - failed to close secondary PS after three trials”
Documented for: 912SE
Likely causes, most common first
- Restricted or improperly sized vent
- Plugged condensate drain
- Obstructed or disconnected pressure tubing
- Failed inducer motor or pressure switch
What you can safely check yourself
- Check outdoor vent terminations for snow, ice or debris
- Check the condensate drain and trap for a clog
When to call a technician
Three failed attempts to make the pressure switch means the venting or the inducer needs a technician's inspection.
A Bryant furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- 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