Home Fault Codes

Bryant Furnace Error Code 31: Meaning and Fix

Applies to: Bryant furnaces with a two-digit status code LED (checked against the Bryant 310AAV manual).

31
How 31 appears on a Bryant furnace display.

Also shown as: 3 short 1 long, 3 short, 1 long flashes

Reading the furnace display

A furnace reports faults on a small status LED on the control board, seen through the sight glass in the blower door, or on a two-digit display. Watch a full cycle of the pattern and count the flashes, including the pause between groups, before you decide what you saw. The code chart is on the label inside the blower door.

This page lists the fault codes this brand documents, with likely causes and a short repair path. The codes apply to model numbers such as 310AAV; check the label on your unit to confirm yours.

What causes 31

How to fix it

If you smell gas, leave the building and call your gas utility from outside; do not touch switches or the furnace. Switch the furnace power off before you open the blower door or touch the igniter or flame sensor, and call a licensed HVAC technician if you are not sure.

The code meaning comes from the manufacturer document listed under Sources. The causes and steps below are general troubleshooting guidance, not the manufacturer's service procedure.

  1. Check outdoors that the vent and intake terminations are not blocked by snow, ice or debris.
  2. Switch the furnace power off and look at the pressure switch tubing for water, kinks or a loose connection.
  3. Do not bypass the pressure switch.
  4. A technician should test the inducer motor and its voltage, the pressure switch, the vent run and the gas pressure.
  5. Restore power and run a heating cycle. If the code returns, call a licensed HVAC technician and give them the code, the board label and the furnace model number.

Questions

What does 31 mean on a Bryant furnace?

Code 31 (3 short, 1 long flash) on a Bryant furnace means the pressure switch did not close, or it reopened. If it stays open for more than five minutes the inducer shuts off for 15 minutes before retrying.

Can I reset the furnace myself?

The control can be reset by switching power off at the furnace switch or breaker for about 30 seconds, which clears some lockouts. If the same code returns, the fault is still present and the control will shut the furnace down again. Never bypass a safety switch to keep it running.

When should I call a technician?

Call a licensed HVAC technician for anything involving gas, the pressure switch, the limit or rollout switches, the igniter, the flame sensor or a control board replacement, or if the code keeps coming back after the simple checks.

Other brands with code 31

The same code can mean something different on another maker's appliance. Check the brand before you act.

Carrier furnacePressure switch did not close or reopenedPayne furnacePressure switch did not close or reopenedRheem tankless water heaterFaulty inlet thermistorRinnai tankless water heaterBurner sensor error

Other Bryant furnace codes

Continuous OffNo power to the control board (LED stays dark)Continuous OnNormal: control board has 24 volt power (LED steady on)Rapid FlashingLine voltage polarity reversed (LED flashing rapidly)11No previous fault code stored12Blower on after power up13Limit circuit lockout

Sources

Part numbers are OEM references; confirm fit by your model number before ordering. Meanings compiled from manufacturer and parts-retailer documentation; see sources below. Unplug the appliance before opening it.

Applies to models including 310AAV.