Goodman Furnace Blinking Red Light Six Times: Causes and Troubleshooting

The blinking red light on a Goodman furnace signaling six flashes is a specific diagnostic code indicating ignition or flame sensing problems. This article explains the causes, safety precautions, step-by-step troubleshooting, and when to call a professional to resolve the issue effectively.

Blink Pattern	Likely Cause	Quick Action
Six Flashes	Ignition Failure / Flame Sense Fault	Inspect ignitor & flame sensor; check gas supply and error history

What Six Blinks Means On A Goodman Furnace

Goodman furnaces use LED flash codes to indicate operational faults. Six blinks typically point to an ignition failure or flame sensing issue, meaning the thermostat called for heat but the burner failed to light or the flame sensor did not detect a flame within the expected time. This is distinct from other codes that indicate motor, pressure switch, or limit issues.

How Goodman Furnace Diagnostics Work

The control board monitors multiple sequences during a heating cycle: inducer operation, ignition attempt, flame detection, and safety timer intervals. If flame is not verified after an ignition attempt, the board will lock out and signal the problem through a repeating LED pattern, such as six blinks for ignition/flame sense faults.

Common Causes Of Six Blinks

Dirty Or Faulty Flame Sensor

A flame sensor coated with carbon or oxidation can fail to register flame even when the burner is lit. Cleaning the sensor often restores proper detection, though a failing sensor may need replacement.

Weak Or Failed Ignitor

If the hot surface ignitor is cracked, glazed, or weak, it will not reach required temperature to ignite the gas. Intermittent ignition attempts or repeated failures are common symptoms.

Gas Supply Issues

Insufficient gas pressure, closed gas valves, or a faulty gas valve can prevent ignition. Confirm the gas is on and other gas appliances function before assuming furnace components are at fault.

Ignition Control Or Board Problems

The furnace control module manages the ignition sequence. Faults or corrupted logic on the board can mismanage spark/ignitor timing or flame verification leading to lockouts and six-blink codes.

Airflow Or Pressure Switch Problems

Restricted airflow, clogged filters, or a failing pressure switch can interrupt the induction/venting sequence, preventing safe ignition timing and causing the control to register a failure.

Safety Precautions Before Troubleshooting

Working on a gas furnace involves safety risks. Always turn off power to the furnace at the service switch or breaker and shut the gas valve if instructed by a technician. If gas odor is present, evacuate and call the gas company or emergency services.

Tools And Materials Needed

• Screwdrivers (Phillips and flat)
• Multimeter for voltage and continuity checks
• Soft cloth or fine-grit sandpaper for flame sensor cleaning
• Replacement parts (ignitor, flame sensor) as required
• Shop vacuum and flashlight

Step-By-Step Troubleshooting Guide

1. Record The Error And Reset

Note the pattern of the red LED blinks and any additional behavior. Attempt a controlled reset by turning the thermostat to off, switching furnace power off for 30 seconds, then back on. Sometimes a reset clears a transient fault, but if six blinks return, continue diagnostics.

2. Verify Gas Supply And Thermostat

Ensure the main gas valve to the furnace is open and other gas appliances operate. Confirm the thermostat is set to heat and has working batteries if applicable. Always confirm simple sources before component-level work.

3. Inspect And Clean The Flame Sensor

Locate the flame sensor—typically a thin metal rod positioned in the burner flame. Remove it carefully and clean with a soft cloth or very fine sandpaper until metallic shine returns. Reinstall and test. Cleaning often remedies false no-flame detection.

4. Inspect The Ignitor

Visually inspect the hot surface ignitor for cracks, white spots, or glazing. Do not touch the ignitor element with bare hands. If damage is visible or resistance measurements are out of spec, replace the ignitor. A weak or broken ignitor commonly causes repeated ignition attempts.

5. Check Venting And Airflow

Confirm intake and exhaust vents are clear of nests, debris, or snow obstructions. Replace dirty air filters and ensure return ducts are unobstructed. Restricted airflow can alter combustion and ignition timing.

6. Test The Pressure Switch And Inducer Motor

With the furnace running through a heat call, verify the inducer motor runs and the pressure switch closes. A multimeter can check continuity across the pressure switch during operation. A failed inducer or pressure switch interrupts the safety sequence.

7. Inspect Wiring And Connectors

Check wiring to the flame sensor, ignitor, and control board for loose connectors, burnt insulation, or corrosion. Secure any loose connections and replace damaged wiring to prevent intermittent faults.

8. Evaluate The Control Board

Inspect the control board for burned components, bulging capacitors, or visible damage. Measure expected voltages and signals per the furnace manual. A faulty board may require professional diagnosis and replacement.

9. Run A Controlled Test Cycle

After remedial steps, run a heat cycle and observe the ignition sequence, listening for the inducer, gas valve opening, ignitor glow, and flame establishment. Monitor whether the flame sensor registers and the red light stops blinking.

When To Replace Parts Versus Call A Technician

Simple tasks like cleaning the flame sensor and replacing the air filter are appropriate for most homeowners. Replace the ignitor if visibly damaged or if resistance testing shows out-of-spec values. For control board issues, gas valve replacement, complex pressure-switch failures, or if the homeowner is uncomfortable with gas/electrical components, hiring a licensed HVAC technician is recommended.

Estimated Costs And Time Frames

Typical DIY parts costs: flame sensor $25–$75, ignitor $40–$150. Professional service visits range from $100–$200 for diagnostics plus parts and labor. Replacement of control boards or gas valves can increase total costs significantly.

Preventive Maintenance To Avoid Future Six-Blink Events

• Change or clean air filters every 1–3 months to maintain airflow.
• Schedule annual furnace inspections and tune-ups by a licensed technician.
• Have the burner assembly and flame sensor inspected and cleaned during service visits.
• Ensure vents and chimneys remain clear year-round.
• Use surge protection to reduce control board damage from electrical events.

How To Read Other Goodman LED Codes

While six blinks indicate ignition/flame sense trouble, other LED patterns correspond to distinct faults such as pressure switch failures, limit switch trips, or blower motor issues. Consult the furnace model-specific manual for an authoritative code chart. Keep a copy of the manual or download it from Goodman for quick diagnostics.

Frequently Asked Questions

Can A Dirty Flame Sensor Cause The Furnace To Click But Not Light?

Yes. A dirty flame sensor may allow the burner to ignite briefly but fail to confirm flame, leading the control to shut off the gas and retry. Cleaning the sensor often resolves this behavior.

Is It Safe To Keep Resetting A Furnace With Six Blinks?

Repeated resets are not recommended. Persistent six-blink faults indicate a safety-related failure. Continuous retries can increase wear and conceal underlying issues. Address root causes or call a professional.

How Long Does Replacing An Ignitor Take?

For a technician, replacing an ignitor typically takes 30–60 minutes, including inspections and a test cycle. Homeowners with decent mechanical skills can often complete the swap in similar time when following safety steps.

Resources And References

Official Goodman installation and service manuals provide model-specific diagnostics and wiring diagrams. State and local codes govern gas appliance service; always use licensed contractors for work that requires permits or gas-line modifications.

Key Takeaways For Homeowners

Six LED blinks on a Goodman furnace most commonly indicate ignition or flame sensing failures. Start with safe, simple checks: reset, verify gas, clean the flame sensor, inspect the ignitor, and ensure proper airflow. For complex electrical or gas-valve issues, enlist a licensed HVAC technician to ensure safe, code-compliant repairs.