Bryant Furnace Flashing Codes: What They Mean and How to Fix Them

Bryant

Summary

  • The LED light on the control board of a Bryant furnace acts as a diagnostic tool, similar to a 'check engine' light in vehicles.
  • Common flash codes include: Code 12 (normal operation), Code 13 (limit circuit lockout due to overheating), and Code 24 (secondary voltage fuse open).
  • Flashing patterns indicate different operational statuses: a steady light means no issues, while a repeating pattern signals the presence of a flash code that needs investigation.
  • If basic troubleshooting (filter replacement, vent checks, etc.) does not resolve the issue, it's advisable to call a certified Bryant technician for further assistance.
  • Each furnace model may have different flash codes; it is recommended to keep the user manual accessible for specific code interpretations.

That Blinking Light Isn’t Random — It’s Talking to You

When your Bryant furnace stops working—or just isn’t behaving right—the first place to look isn’t your thermostat. It’s that tiny flashing LED light on the control board. Think of it as your furnace’s version of a “check engine” light.

Here’s how to read what it’s telling you—and what to do next.

Step 1: Find the Flash Code

Where to Look

Open the lower front panel of your furnace. Inside, you’ll find a control board with a small LED light. Right nearby, you should see a flash code legend printed on a sticker.

What the Flashing Means

The LED blinks in a pattern:

  • One-digit codes blink X times, pause, then repeat.

  • Two-digit codes blink X short flashes, pause, then Y short flashes.

Example: Three short blinks, pause, then one = Code 31

Bryant furnace flashing light codes

Step 2: Decode the Flashing Light

Here are the 7 most common Bryant furnace flash codes and what they mean in plain English:

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🔁 Code 12 – Blower On After Power-Up

Meaning: Normal startup behavior
What to do: Nothing. Your system is just running its blower briefly after powering on.

🔥 Code 13 – Limit Circuit Lockout

Meaning: Your furnace overheated multiple times and shut down to protect itself.

Common Causes:

  • Dirty air filter

  • Closed or blocked vents

  • Overworked blower

What to do:

  • Replace the air filter

  • Make sure all vents are open

  • Turn power off and back on to reset

⚡ Code 24 – Secondary Voltage Fuse Open

Meaning: Your control board isn’t getting low-voltage power.

Common Causes:

  • Blown 3A fuse on the control board

  • Damaged or shorted thermostat wires

What to do:

  • Check and replace the fuse if needed

  • Inspect wires for visible damage

  • If it blows again, call a pro

🌬️ Code 31 – Pressure Switch Fault

Meaning: The furnace couldn’t prove proper airflow for combustion.

Possible Issues:

  • Clogged vent pipe (inlet/exhaust)

  • Water backup in condensate line

  • Pressure switch hose is dirty or kinked

What to do:

  • Check for snow, leaves, or debris at vent terminations

  • Empty drain traps

  • If it persists, have a tech check the switch and tubing

🔥 Code 34 – Ignition Proving Failure

Meaning: Your furnace tried to light but couldn’t confirm a flame.

Common Causes:

  • Dirty or corroded flame sensor

  • Faulty igniter

  • Gas supply issue

What to do:

  • Gently clean the flame sensor with fine sandpaper

  • Ensure the gas valve is open

  • Still failing? Time for a service call

💨 Code 41 – Blower Motor Fault

Meaning: The blower didn’t start when it should have.

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What to check:

  • Loose wiring at the motor

  • Failed capacitor

  • Control board signal issues

What to do: This one typically requires a technician.

🌡️ Code 44 – Limit Circuit Fault

Meaning: The system overheated momentarily but recovered.

What to do:

  • Make sure filters and vents are clean and open

  • Monitor for recurrence—if it comes back, call a pro

Step 3: Know When to Worry (and When Not To)

Not all flashing is bad. Here’s a quick guide:

Flash Pattern What It Means Do You Need to Worry?
Steady light System powered, no issue ✅ All good
Slow flash (1/sec) Furnace idle ✅ Normal
Fast flash (3–4/sec) Call for heat in progress ✅ Still okay
Repeating pattern Flash code active 🚨 Time to investigate

 

Step 4: When to Call for Help

If you’ve:

  • Replaced the filter

  • Reset power

  • Checked the vent pipes

  • Cleaned the flame sensor

…and your system still throws codes or fails to start, it’s time for a certified Bryant technician. They’ll have the tools to test pressure switches, motors, and control board signals.

Bonus Tip: Keep Your Manual

Every furnace model has slight differences in its code legend. Keep your Bryant user manual handy or download one from the Bryant website based on your exact model number.

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Kelsey Neff
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