Goodman Gas Furnace Error Codes and Troubleshooting Guide

The following guide explains common Goodman gas furnace codes, LED blink sequences, diagnostic steps, and practical troubleshooting tips to help identify and resolve issues safely. This resource is intended to clarify what each code means and when to perform DIY fixes versus contacting a licensed HVAC technician.

Code	LED Pattern	Common Cause	Recommended Action
Err 1 / 1 Blink	1 Blink Pause	Power or limit switch fault	Check power, reset, inspect limit and door switches
Err 2 / 2 Blinks	2 Blinks Pause	Pressure switch or inducer issue	Inspect venting, pressure tubing, and inducer motor
Err 3 / 3 Blinks	3 Blinks Pause	Flame sensed when not commanded or failed flame	Check ignition system and flame sensor, clean sensor
Err 4 / 4 Blinks	4 Blinks Pause	Open high-limit or rollout switch tripped	Check filter, airflow, inspect heat exchanger area
Err 5 / 5 Blinks	5 Blinks Pause	Blower or fan circuit fault	Inspect blower motor, capacitor, and wiring
Err 6 / 6 Blinks	6 Blinks Pause	Stuck gas valve or ignition failure	Check gas supply, coil, and ignition transformer

How Goodman Gas Furnace Codes Work

Goodman furnaces use an LED diagnostic light on the control board to display error conditions via blink patterns. Each blink sequence corresponds to a specific fault, allowing technicians and homeowners to narrow down the problem before taking action.

The control board monitors inputs like thermistor, flame sensor, pressure switch, limit switches, and blower operation. When an abnormal condition is detected, the board locks out the furnace and displays a code to prevent unsafe operation.

Common Goodman Error Codes And Meanings

1 Blink — Power Or Control Board Issue

One blink usually indicates a power problem or a short interruption in control voltage. This might be caused by loose wiring, blown fuses, or brief power loss. Verify incoming power and all control connections before further diagnosis.

2 Blinks — Pressure Switch Or Inducer Problem

Two blinks point to an inducer motor failure, pressure switch stuck, or blocked venting. Common causes include clogged intake/exhaust, disconnected pressure hose, or a failing inducer motor.

3 Blinks — Flame Sensing Or Ignition Fault

Three blinks typically indicate the control did not sense flame when gas was supplied, or it sensed flame when not expected. This often implicates the flame sensor, ignitor, or gas valve. Cleaning the flame sensor can resolve many of these issues.

4 Blinks — High Limit Or Rollout Switch Tripped

Four blinks mean the high-limit switch opened, indicating overheating or restricted airflow. Dirty filters, closed vents, or blocked return ducts are frequent causes. The switch may require resetting or replacement if it continues to trip.

5 Blinks — Blower Motor Or Circuit Fault

Five blinks signal a problem with the induced draft motor circuit or blower motor. Capacitor failure, bearing wear, or open motor windings are possible reasons. Verify voltage to the motor and inspect the capacitor and wiring harness.

6 Blinks — Gas Valve Or Ignition Transformer Issue

Six blinks indicate gas valve coil or ignition transformer problems. This may reflect a stuck valve, weak gas supply, or failed transformer. Confirm gas supply at the shutoff and inspect voltage to the gas valve coil.

How To Read The LED On Your Goodman Furnace

Locate the control board access panel and find the status LED; it often blinks in sequences separated by brief pauses. Count the number of flashes in each cycle to identify the code. Refer to the furnace’s model manual for model-specific codes and sequences since older or newer boards may vary.

Initial Safety Checks Before Troubleshooting

• Turn off power at the furnace switch or breaker before opening panels.
• Ensure the gas supply is on and the thermostat is set correctly.
• Use a multimeter for voltage checks and only if comfortable with electrical work.
• If a gas smell is present, evacuate the area and call the gas company.

Step-By-Step Troubleshooting For Common Codes

Power And Control Board Faults (1 Blink)

Confirm the furnace has 120V at the power input. Inspect fuse or circuit breaker and replace a blown 3A or 5A fuse on the control board if present. Examine wiring connectors for corrosion or loose pins.

Inducer And Pressure Switch Issues (2 Blinks)

Check vent terminations for debris, animal nests, or ice. Inspect the pressure tubing for kinks or disconnections. Test the inducer motor for operation and check continuity. Replace the pressure switch if it fails to close under vacuum.

Ignition And Flame Problems (3 Blinks)

Turn off power and remove the flame sensor. Clean it with fine sandpaper or steel wool to remove oxidation. Inspect the hot surface ignitor or spark electrode for cracks or wear. Verify proper grounding for flame sensing circuits.

High Limit Trips And Airflow Problems (4 Blinks)

Replace a dirty air filter and check return-air registers for obstructions. Inspect the blower wheel and motor for dust buildup or damage. If the heat exchanger has signs of significant soot or rust, schedule professional inspection.

Blower And Motor Faults (5 Blinks)

Test the blower capacitor for the correct microfarad rating and replace if out of tolerance. Check motor current draw against nameplate specifications. Lubricate bearings if applicable to the model, or replace a noisy motor.

Gas Valve And Ignition Transformer (6 Blinks)

Confirm 24VAC is present at the gas valve coil when the thermostat calls for heat. If voltage is present and the valve doesn’t open, the valve may be defective. Verify the ignition transformer provides the required voltage to the ignitor or spark assembly.

Resetting The Furnace: When And How

Resetting can clear transient faults but should be used cautiously. Power cycle by switching off the furnace for 30 seconds to 5 minutes and restoring power. Repeated resets without diagnosing the root cause can mask a dangerous condition and may further damage components.

Maintenance To Prevent Error Codes

• Replace air filters every 1–3 months depending on usage and filter type.
• Keep vent terminations and combustion air openings clear of debris.
• Schedule annual professional tune-ups to check flame integrity, gas pressure, and controls.
• Clean the flame sensor, burners, and blower assembly during maintenance visits.

When To Call A Professional

Call a licensed HVAC technician if the code indicates a potential gas leak, cracked heat exchanger, failed gas valve, or if the homeowner lacks tools or training for safe electrical/gas work. Complex issues and safety-critical failures require professional diagnostics.

Model Variations And Technical Resources

Goodman uses different control boards across model lines; some codes or LED behaviors vary. Consult the specific model’s installation and service manual for exact code definitions. Manufacturers’ manuals and the Goodman distributor website provide wiring diagrams and control board part numbers.

Warranty And Replacement Parts

Check the furnace’s serial number and warranty status before replacing major components. Goodman typically offers limited warranties on heat exchangers and parts, but labor is often excluded. Use OEM replacement parts or equivalent quality components.

Frequently Asked Questions About Goodman Furnace Codes

Can A Homeowner Replace A Flame Sensor?

Yes, replacing a flame sensor is often straightforward: power off, remove the old sensor, install the new sensor in the same position, and reconnect wiring. Cleaning first is recommended as many issues are resolved by cleaning alone.

Is It Safe To Run A Furnace With A Code?

It depends on the code. Some codes indicate non-critical conditions, while others indicate unsafe operation. If the furnace is locked out for flame failure, gas valve problems, or heat exchanger concerns, do not attempt to run it until inspected by a technician.

How Much Does Repair Typically Cost?

Costs vary: a simple flame sensor replacement can range from $100–$250 including labor, while inducer motor or gas valve replacements can be $400–$1,200. Always get multiple quotes and ensure technicians are licensed and insured.

Key Takeaways For Homeowners

• Identify the code by counting LED blinks and consult the furnace manual.
• Perform basic safety checks and simple maintenance like filter replacement and flame sensor cleaning.
• Reset only after verifying safety and avoid repeated resets without diagnosis.
• Call a licensed technician for gas, heat exchanger, or complex electrical issues.

Understanding Goodman gas furnace codes empowers homeowners to make informed decisions about troubleshooting, maintenance, and repairs while prioritizing safety and efficient operation. For model-specific assistance, reference the furnace manual or contact an authorized Goodman service provider.