Six Flashes on Goodman Furnace: Meaning, Troubleshooting, and Fixes

The Goodman furnace control board uses LED flash codes to indicate specific faults; six flashes on Goodman furnace typically point to an induced draft pressure switch or venting issue. This article explains what the six-flash code means, how to diagnose it safely, step-by-step troubleshooting, possible repairs, and when to call a qualified HVAC technician.

Flash Code	Common Meaning	Urgency
Six Flashes	Induced Draft Pressure Switch Or Venting/Exhaust Problem	Medium-High: Requires Prompt Diagnosis

What The Six Flashes On Goodman Furnace Means

Goodman furnace LED flash codes are a diagnostic language from the control board; six flashes usually indicate that the furnace failed to verify proper flue draft via the induced draft pressure switch during the ignition sequence.

When the furnace starts, the draft inducer motor creates negative pressure in the venting system; the pressure switch must close to signal safe venting. Six flashes mean the control board did not see that switch close or saw an inconsistent signal.

Common Causes Of Six Flashes

Blocked Or Restricted Venting

Debris, animal nests, heavy snow, or collapsed vent pipes can restrict airflow. Restricted venting prevents the inducer from creating the correct pressure differential and triggers the six-flash fault.

Faulty Induced Draft Pressure Switch

The pressure switch itself can fail electrically or mechanically. A weak diaphragm, cracked housing, or internal short can keep the switch from closing even when draft is correct.

Disconnected Or Crimped Pressure Tubing

Flexible tubing from the inducer housing to the pressure switch can become disconnected, cracked, or pinched during service. A compromised tube will give incorrect pressure readings.

Inducer Motor Problems

If the inducer motor does not spin at the correct speed due to a failed capacitor, motor fault, or power issue, the pressure necessary to close the switch may not be achieved.

Obstructions In Heat Exchanger Or Flue

Corrosion, soot buildup, or foreign objects inside the heat exchanger or flue can alter airflow paths and prevent the pressure switch from sensing the correct draft.

Control Board Or Wiring Issues

Faulty wiring, loose connectors, or a malfunctioning control board may misinterpret the pressure switch signal, resulting in six flashes even when the pressure switch is functional.

Safety First: Precautions Before Troubleshooting

Working on gas furnaces involves risks including gas leaks, carbon monoxide, and electrical hazards. Shut off power and gas before inspecting components unless a visual check requires power on for observation only.

Use a multimeter only if qualified. If any smell of gas, vacate the home and call the gas company or emergency services. When in doubt, contact a licensed HVAC technician.

Tools And Materials Needed

• Multimeter (voltage and continuity)
• Manometer or digital pressure gauge (for precise pressure tests)
• Screwdrivers and nut drivers
• Flashlight and mirror
• Replacement tubing, pressure switch, or inducer motor (as needed)
• Vacuum or brush for vent cleaning

Step-By-Step Troubleshooting For Six Flash Code

Initial Visual Inspection

Check the exhaust and intake terminations outside for birds’ nests, debris, snow, or ice. Inspect vent pipes and joints for disconnection or visible damage.

Verify Inducer Operation

Restore power and run the furnace through a call for heat. Observe whether the inducer motor starts and reaches expected speed. Listen for unusual noises like grinding or scraping that indicate motor or bearing failure.

Inspect Pressure Tubing

Locate the small rubber tubing from the inducer housing to the pressure switch. Check for disconnections, kinks, cracks, or blockages. Replace tubing if brittle or damaged.

Test The Pressure Switch With A Gauge

Attach a manometer to the pressure switch port to measure negative pressure during inducer operation. Compare readings to the furnace’s specifications in the tech sheet. If pressure is within range but the switch doesn’t close, suspect a faulty switch.

Check Switch Continuity And Voltage

With power off, test the pressure switch for continuity when the inducer is running (or apply vacuum to the switch to simulate pressure). Use a multimeter to verify the switch closes electrically as specified.

Examine Flue And Heat Exchanger

Remove access panels to visually inspect the heat exchanger and flue path for soot, debris, or signs of corrosion. Blockages inside the heat exchanger or flue can alter draft and cause the fault.

Test Inducer Motor Current Draw

Use a clamp meter or compare observed motor performance to nameplate specs. Low or high current draw can indicate electrical problems, failing motor, or mechanical binding that reduces output pressure.

Inspect Control Board And Wiring

Check harness connectors at the pressure switch and control board for corrosion or loose pins. Test the control board outputs to ensure it is commanding the inducer correctly and sensing the switch input.

Common Repairs And Replacements

Replace Pressure Tubing

Tubing is inexpensive and often resolves false six-flash faults. Use equivalent high-temperature tubing and ensure secure fittings at both ends.

Replace Pressure Switch

If the switch fails electrical or vacuum tests, replace it with the correct OEM or approved equivalent part. Confirm the new switch’s opening/closing pressures match the furnace specification.

Service Or Replace Inducer Motor

If the inducer motor is noisy, slow, or draws abnormal current, repair or replace it. Verify venting operation after replacement and confirm the six-flash code is cleared.

Clear Or Repair Venting

Remove obstructions from intake/exhaust terminations and vent runs. Repair damaged or collapsed vent pipes and ensure proper slopes and supports. For complex systems, consult venting diagrams in the installation manual.

Control Board Replacement

Control boards rarely fail but can misread inputs. Replace the control board only after ruling out simpler causes and confirming the board is at fault.

When To Call An HVAC Professional

Contact a licensed technician if gas, carbon monoxide concerns, complex disassembly, or electrical diagnosis beyond basic checks is required. When multiple components fail or the issue recurs after repairs, a professional can perform advanced diagnostics and ensure safe, code-compliant repairs.

Warranty considerations also matter; repairs by unqualified individuals can void manufacturer warranties on Goodman furnaces. For in-warranty units, use authorized service providers.

Preventive Maintenance To Avoid Six-Flash Problems

• Schedule annual professional tune-ups to inspect combustion, venting, and safety devices.
• Keep intake and exhaust terminations clear of debris, snow, and vegetation.
• Inspect vent runs and support straps periodically for damage or sagging.
• Replace brittle pressure tubing during routine service intervals.
• Change air filters regularly to maintain airflow and prevent stress on combustion components.

Estimating Repair Costs

Cost varies by region and the failed component. Typical national ranges: pressure tubing or minor cleaning: $50–$200; pressure switch replacement: $150–$350; inducer motor replacement: $300–$700; control board replacement: $250–$600. Diagnostic fees may apply.

Always get written estimates and verify technician credentials and warranty terms before authorizing work.

Frequently Asked Questions About Six Flashes On Goodman Furnace

Can A Dirty Filter Cause Six Flashes?

A very dirty filter can reduce overall airflow, but the six-flash code specifically relates to draft pressure. While poor airflow stresses the system, the direct cause is usually venting, pressure switch, or inducer issues.

Will Resetting The Furnace Clear The Code Permanently?

Resetting can temporarily clear the fault if the condition was intermittent. If the root cause persists, the code will return. Use reset only as a diagnostic step, not a permanent fix.

Is Carbon Monoxide A Risk With A Six-Flash Fault?

Yes. Improper venting can allow combustion gases to backdraft into living spaces. If there is any concern about CO, evacuate and seek emergency help. Install and maintain CO detectors on every level of the home.

Are DIY Fixes Advisable?

Basic checks like clearing vents and inspecting tubing are reasonable for homeowners. Electrical, gas, and combustion system repairs should be left to licensed professionals to ensure safety and code compliance.

Key Takeaways

Six flashes on a Goodman furnace most commonly indicate an induced draft pressure switch or venting problem. Systematic diagnosis—visual inspection, pressure testing, switch continuity checks, and inducer motor evaluation—will reveal the cause. Prompt action avoids safety hazards and further damage.

For complex issues or safety concerns, contact a licensed HVAC technician and consider regular maintenance to reduce recurrence of the six-flash fault.