Bryant Furnace Code 23: Meaning, Causes, Troubleshooting, and Fixes

Bryant Furnace Code 23 Appears On Many Bryant/Carrier Gas Furnace Control Boards To Indicate A Safety Or Venting Problem That Prevents Normal Ignition Or Flame Operation. This Article Explains What Code 23 Typically Means, Common Causes, Step‑By‑Step Troubleshooting, Safety Precautions, And When To Call A Licensed HVAC Technician.

Item	Summary
Typical Meaning	Combustion Air, Venting, Or Safety Switch Fault (Pressure Switch, High Limit, Or Rollout)
Common Causes	Blocked Vent/Flue, Faulty Pressure Switch, Broken Inducer Motor, Tripped Rollout/Limit Switch, Loose Wiring, Control Board Error
Recommended Action	Basic Checks By Homeowner, Replace Parts Or Service By Technician For Safety

What “Code 23” Usually Means

Code 23 On Bryant Furnaces Is A Generic Fault Indication Used By Control Boards To Signal A Problem In The Combustion Sequence Or A Safety Device Has Tripped. Exact Definitions Vary By Model And Control Board, But It Most Often Points To Issues With The pressure switch, inducer motor/venting, Or A high‑limit/rollout safety switch.

How To Confirm The Code And Model‑Specific Definition

Locate The Furnace Model/Serial Plate And The Control Board Sticker Or Manual For The Exact Error Code Table. Many Bryant Units Use Carrier Control Boards, And The Service Manual Lists Blink Patterns Or Digital Codes With Precise Meanings.

Steps To Find The Correct Definition

• Record The Exact Blink Pattern Or Digital Display Code.
• Check The Furnace Data Plate For Model/Serial Numbers.
• Search The Manufacturer Manual Or Printed Label Inside The Access Panel.
• If Unavailable, Note Symptoms (No Ignition, Incomplete Draft, Inducer Not Running) For Diagnosis.

Common Causes Of Code 23

Several Faults Can Produce Code 23. Below Are The Most Frequent Causes And How They Affect Operation.

Blocked Or Restricted Venting

A Blocked Chimney, Capped Vent, Bird Nest, Or Ice Blockage On A High‑Efficiency Condensing Furnace Can Prevent Proper Draft, Causing The Pressure Switch Not To Close And Triggering Code 23.

Faulty Pressure Switch

The Pressure Switch Verifies That The Inducer Is Creating Negative Pressure For Safe Combustion. A Failed Or Stuck Pressure Switch, Cracked Hose, Or Incorrect Switch Rating Causes The Control To Lock Out.

Inducer Motor Or Fan Failure

If The Inducer Motor Does Not Run Or Runs Slowly Due To Motor Failure, Capacitor, Or Power Loss, The Pressure Switch Won’t See Proper Draft And Code 23 Can Result.

High‑Limit Or Rollout Switch Tripping

An Overheating Condition Or Flame Rollout Can Trip Safety Limits. This Will Shut Down the gas valve and report a fault such as Code 23 on some boards.

Gas Valve, Ignition, Or Flame Failure

In some models, repetitive ignition failures or flame signal problems will present as a safety lockout similar to Code 23; however, this is less common than pressure/vent issues.

Wiring Or Control Board Problems

Loose Or Corroded Wiring, Broken Connector Pins, Or A Faulty Control Board Can Report Erroneous Codes Including 23. Visual Inspection Often Reveals These Issues.

Safety First: Precautions Before Troubleshooting

Working On Gas Furnaces Can Be Dangerous. Turn Off Power To The Furnace At The Breaker And Shut Off The Gas When Opening Panels Or Testing Components. If The Home Smells Of Gas, Evacuate And Call The Gas Company Or 911. When In Doubt, Contact A Licensed HVAC Technician.

Homeowner Troubleshooting Checklist

These Steps Help Identify Simple, Non‑Technical Problems That Homeowners Can Safely Verify Before Calling A Technician.

1. Reset The Furnace: Turn Off Power For 30 Seconds, Then Restore Power To See If The Code Clears.
2. Check Vents And Exhaust: Inspect Outside Vent Terminals For Obstructions (Leaves, Snow, Nests).
3. Inspect Intake Air: Ensure Combustion Air Intake Is Clear And Not Blocked By Debris.
4. Check Furnace Filters: A Clogged Filter Can Cause Overheat Conditions That Trip Limits.
5. Listen For Inducer: When Furnace Calls For Heat, Listen For The Inducer Motor Starting; If Silent, Note That Symptom.
6. Visual Wiring Check: With Power Off, Look For Loose Connectors, Burn Marks, Or Disconnected Hoses On The Pressure Switch.

Advanced Diagnostic Steps For Technicians

Technicians Use Tools And Procedures Beyond Typical Homeowner Scope. These Steps Require Training And Gas‑specific Safety Practices.

Measure Pressure Switch Operation

Use A Manometer To Check Inducer Vacuum And Confirm The Pressure Switch Closes At The Correct Differential. Replace The Switch If It Fails To Close Or Shows Inconsistent Behavior.

Test The Inducer Motor And Capacitor

Measure Line Voltage To The Inducer, Check Motor Amp Draw Against Specifications, And Test Or Replace The Run Capacitor If Inducer Starts Slowly Or Draws Excess Current.

Inspect Venting Integrity

Perform A Visual And Leak Test On Vent Pipes And Heat Exchanger Connections. On High‑efficiency Units, Ensure Condensate Drain And PVC Venting Are Not Collapsing Or Blocked.

Check High Limit And Rollout Switches

Verify Switch Operation With A Multimeter And Investigate Root Causes For Tripping Such As Restricted Airflow Or Flame Rollout From A Faulty Burner Or Heat Exchanger Problem.

Diagnose Control Board And Wiring

Scan For Fault Codes, Verify Connector Voltages, And Inspect For Shorted Or Open Circuits. Replace The Control Module Only After Confirming The Underlying Fault Is Resolved.

Common Repairs And Estimated Costs

Costs Vary Widely By Region And Furnace Model. The Estimates Below Provide A General Range For U.S. Homeowners.

Repair	Typical Cost Range
Pressure Switch Replacement	$120–$300 Including Labor
Inducer Motor Replacement	$250–$600 Including Labor
Venting Repair/Clearing	$75–$400 Depending On Complexity
High Limit/Rollout Switch Replacement	$100–$300 Including Labor
Control Board Replacement	$300–$900 Including Labor

When To Call A Professional

Call A Licensed HVAC Technician Immediately If There Is A Persistent Gas Odor, Visible Flame Rollout, Repeated Lockouts After Simple Checks, Or If The Homeowner Is Uncomfortable Performing Basic Inspections. Complex Electrical, Gas, And Heat Exchanger Issues Require Certified Service For Safety And Warranty Compliance.

Preventive Maintenance To Avoid Code 23

Regular Maintenance Reduces The Chance Of Safety Lockouts And Extends Furnace Life. A Seasonal Service Visit Pays Off By Catching Problems Early.

• Schedule Annual Professional Tune‑Ups Including Combustion Analysis.
• Replace Air Filters Every 1–3 Months As Recommended.
• Keep Outdoor Vents Clear Of Debris And Snow.
• Ensure Proper Furnace Room Ventilation And Combustion Air Supply.
• Address Strange Noises Or Irregular Cycling Promptly.

Key Takeaways And Best Practices

Code 23 Signals A Safety/Combustion Issue: Most Often Related To Pressure Switch, Inducer, Or Venting. Homeowners Can Safely Perform Visual Vent Checks, Reset Power, And Replace Filters.

Document Symptoms And Model Info: Note The Exact Code Pattern And Furnace Model Before Calling For Service To Speed Diagnosis.

Safety Is Paramount: If There Is Any Question About Gas, Flames, Or Heat Exchanger Integrity, Shut Off The System And Contact A Licensed Technician.

Resources And Manufacturer Links

For Model‑Specific Diagnostics Consult The Bryant Or Carrier Owner’s Manual And The Control Board Label Inside The Furnace. Professional HVAC Associations And Local Utility Efficiency Programs Also Provide Guidance On Safety And Rebates For Replacements.