Goodman Furnace Light Codes and Troubleshooting Guide

The following guide explains Goodman furnace light codes, what each flashing pattern means, and how homeowners and HVAC technicians can safely diagnose and address common issues. Understanding these codes helps pinpoint malfunctions quickly and decide whether a simple reset or professional service is needed.

Indicator Pattern	Meaning	Common Actions
Steady Amber	24V Power On / Normal Standby	None—Normal operation
1 Flash Amber	Pressure Switch Closed/Opening Delay	Check venting and inducer motor
2 Flashes Amber	Open High-Limit/Flame Rollout	Inspect heat exchanger, airflow
3 Flashes Amber	Ignition Lockout/Repeated Failures	Check ignition system, call tech
4 Flashes Amber	Pressure Switch Stuck Open	Check pressure tubing, draft inducer
5 Flashes Amber	Open Flame Sensor/Ignition Failure	Clean or replace flame sensor
6 Flashes Amber	Blower Door Switch Open	Ensure access panel seated correctly

How Goodman Furnace Light Codes Work

Goodman furnaces use an indicator LED—often amber or red—to communicate fault conditions through flash patterns. The furnace control board monitors sensors such as the pressure switch, flame sensor, ignition module, and limit switches.

When the control board detects an abnormal condition, it flashes a code. Each code corresponds to a specific fault, aiding diagnostic steps and reducing troubleshooting time for technicians and savvy homeowners.

Locating The Indicator Light And Control Board

The indicator light and diagnostic label are typically located behind the service panel or on the control board inside the furnace access door. The diagnostic label or the furnace manual usually lists the meaning of each flash code for that model.

Before inspecting, turn off all power to the furnace at the thermostat and the service switch. Always follow safety precautions and consult the model-specific manual for exact procedures.

Common Goodman Furnace Light Codes And Their Meanings

Steady Amber Or Green Light

A steady light often indicates that the 24-volt transformer is supplying power and the control board is in standby. This is a normal state when the thermostat is not calling for heat.

1 Flash — Pressure Switch / Inducer Delay

One flash usually signals a pressure switch or inducer motor issue. The control board may be waiting for the pressure switch to close during the start sequence.

Common causes include blocked venting, a failing inducer motor, or restricted intake. Inspect vent termination and pressure tubing for obstructions, then test the inducer motor operation.

2 Flashes — High Limit Or Flame Rollout

Two flashes commonly indicate a high-limit trip or flame rollout condition, meaning the furnace detected unsafe temperatures or combustion gas escaping the heat exchanger.

Possible issues include dirty air filters, blocked return ducts, cracked heat exchanger, or blocked flue. Immediate attention is recommended because flame rollout and heat exchanger cracks are safety hazards.

3 Flashes — Ignition Lockout

Three flashes typically mean ignition lockout after repeated failed attempts to establish flame. The furnace attempted ignition multiple times and shut down to prevent unsafe conditions.

Possible causes include a bad igniter, faulty gas valve, weak flame signal, or blocked gas supply. Troubleshooting should begin with checking the igniter and flame sensor functionality.

4 Flashes — Pressure Switch Stuck Open

Four flashes often indicate the pressure switch remains open when it should close, preventing the gas valve from opening. This points to venting problems, a failed pressure switch, or induction motor issues.

Check for blocked venting, disconnected pressure tubing, and test the pressure switch continuity. Replace the pressure switch if it fails electrical testing.

5 Flashes — Flame Sense Failure Or Ignition Failure

Five flashes frequently represent a flame sensing problem. The control board does not detect a sustained flame after ignition attempts.

Common remedies include cleaning or replacing the flame sensor, ensuring proper ground and sensor positioning, and verifying the ignition control module is operating correctly.

6 Flashes — Blower Door Or Limit Switch Open

Six flashes usually indicate the door switch or a limit switch is open, telling the control board the furnace access panel is not properly secured or an overtemperature limit was tripped.

Confirm the access panel is seated and the door switch actuates. For limit trips, inspect airflow, filter condition, and possible blower motor issues.

Other Flash Patterns And Manufacturer Variations

Goodman models may vary in exact flash code definitions. Some control boards use red LEDs and different count timings. Always consult the furnace’s data plate or owner’s manual for model-specific diagnostics.

If a flash pattern is not listed, search the exact furnace model number plus “diagnostic codes” for accurate, authoritative information.

Step-By-Step Troubleshooting Checklist

1. Safety First: Turn off power to furnace before opening panels.
2. Locate the diagnostic LED and observe the flash pattern for several cycles.
3. Consult the model-specific manual or label to confirm code meaning.
4. Perform visual checks: vents, flue, air filter, access panels, and pressure tubing.
5. Test components with a multimeter: pressure switch continuity, limit switch, and ignition transformer.
6. Clean the flame sensor with fine emery cloth if flame failure codes appear.
7. Replace failed components: igniters are fragile and often replaced if cracked or weak.
8. If suspected heat exchanger damage or flame rollout, stop operation and schedule immediate professional service.

Tools And Parts Typically Needed

• Multimeter for voltage and continuity checks.
• Manometer or smoke pencil for venting and draft checks.
• Replacement flame sensor, igniter, or pressure switch (model-specific).
• Small hand tools and manufacturer-approved replacement parts.
• Shop vacuum and soft cloth for cleaning dust and debris.

When To Call A Professional

Some issues require licensed HVAC technicians. Call professional help if the furnace shows flame rollout, cracked heat exchanger, persistent ignition lockouts, gas valve or combustion system faults, or if the homeowner lacks tools or confidence to test electrical components safely.

Technicians will perform combustion analysis, heat exchanger inspection, gas pressure testing, and advanced control board diagnostics that go beyond basic homeowner checks.

Preventive Maintenance To Reduce Fault Codes

Regular maintenance lowers the chance of faults that trigger Goodman furnace light codes. Recommended tasks include annual professional tune-ups, filter changes every 1–3 months, and keeping vents clear of debris.

Key preventive steps: replace filters, clean burners and the flame sensor annually, inspect venting for nesting or blockages, and verify the inducer motor spins freely.

Model Variations And How To Find Accurate Code Lists

Goodman furnace models and control boards vary; common boards include Goodman/Amana and various OEM-supplied control modules. Exact flash codes may differ in meaning and number of flashes.

Locate the model and serial number on the furnace data plate, then search the manufacturer website or service manual for the correct diagnostic chart. Service bulletins and OEM part sheets are also reliable resources.

Safety Warnings And Best Practices

Never operate a furnace with suspected combustion leaks or a cracked heat exchanger. Carbon monoxide risk is significant with combustion system failures.

Disconnect power before servicing electrical components. If gas odour is present, evacuate the premises and call the gas utility or emergency services immediately.

Example Real-World Scenarios

Scenario A — Furnace Shows Three Flashes And Won’t Stay On

Three flashes indicate ignition lockout. The homeowner checked the igniter visually and found it intact but old. A technician tested the igniter resistance and found it out of range. Replacing the igniter resolved the issue.

Scenario B — Two Flashes After Long Runtime

Two flashes pointed to a high-limit trip. The air filter was heavily clogged and return vent blocked. After replacing the filter and clearing obstructions, the furnace operated normally and no further trips occurred.

Scenario C — Four Flashes With No Inducer Spin

Four flashes suggested a pressure switch stuck open. Inspection revealed a cracked pressure hose and a seized inducer motor. Replacing the hose and inducer motor cleared the fault codes.

Resources For Further Reading

• Goodman Manufacturing Official Website — product manuals and support resources.
• AHRInet — technical standards and HVAC industry resources.
• EPA Indoor Air Quality — safety guidance on combustion appliances.

For accurate diagnostics, always cross-reference the specific Goodman furnace model number with official documentation. Proper identification of light codes and measured troubleshooting prevents unnecessary part replacement and ensures safe furnace operation.