Pilot Light Went Out on Furnace: Causes, Troubleshooting, and Safety Tips

The pilot light went out on a furnace can disrupt heating and pose safety concerns for homeowners. This article explains why pilot lights go out, safe troubleshooting steps, how to relight many common furnace pilots, when to call a professional, and preventive maintenance to reduce recurrence. The guidance is geared to U.S. households and focuses on practical, safety-first actions.

Issue	Likely Cause	Immediate Action
Pilot Light Went Out Frequently	Drafts, dirty thermocouple, or weak gas flow	Inspect for drafts, clean components, call technician
No Gas To Pilot	Closed gas valve or gas supply problem	Check valve, contact gas company if unsure
Pilot Won’t Stay Lit	Faulty thermocouple or gas control valve	Replace thermocouple or call HVAC pro

Why The Pilot Light Went Out On Furnace

Understanding why the pilot light went out on a furnace helps prioritize safe actions. Common reasons include drafts that blow the flame out, a weak or irregular gas supply, a dirty pilot orifice restricting flow, or a failing thermocouple that detects flame and keeps the gas valve open.

Other causes include a closed or partially closed gas valve, problems with the gas regulator or supply line, and venting or combustion-air issues that prevent flame stability. Age and corrosion of components also increase the chance the pilot light goes out.

Safety First: Immediate Steps If The Pilot Light Went Out

If the pilot light went out on a furnace, take immediate safety precautions before attempting any troubleshooting or relighting steps. Do not attempt to relight if there is a strong smell of gas; evacuate the building and call the gas company or emergency services.

Turn off the furnace switch and the gas control knob if accessible. Open windows and doors to ventilate the area and avoid creating electrical sparks. Use a flashlight rather than matches or lighters until the area is clear of gas odor.

How To Safely Relight A Pilot Light On A Furnace

Many older furnaces have a manual pilot that homeowners can relight safely if there is no gas odor. Follow the manufacturer’s instructions on the furnace nameplate or owner’s manual. The general process is consistent across models but always verify model-specific steps first.

Tools And Preparations

• Long-reach fireplace lighter or long-stem match
• Screwdriver or small wrench (if access panels are secured)
• Flashlight
• Manufacturer’s manual or gas control instructions

Step-By-Step Relighting Procedure

1. Turn Off The Furnace: Switch the furnace to OFF and wait five minutes to allow any residual gas to dissipate.
2. Locate The Pilot Assembly: Access the pilot light area—usually behind a small panel near the burners.
3. Turn Gas Control To Pilot: Rotate the gas control knob to the PILOT position; press and hold the knob to allow gas flow.
4. Light The Pilot: While holding the knob, use the lighter to ignite the pilot. Continue holding for 20–60 seconds to allow the thermocouple to heat.
5. Release And Test: Release the knob. If the pilot remains lit, turn the control to the ON position and restore power to the furnace. Monitor the flame for stability.

If the pilot will not stay lit after multiple attempts, or if the gas control knob feels abnormal, stop and contact a licensed HVAC technician.

Common Component Failures When Pilot Light Went Out On Furnace

When the pilot light went out on a furnace repeatedly, certain components are often responsible. Recognizing these helps decide whether a DIY fix is appropriate or professional service is needed.

Thermocouple Or Thermopile

The thermocouple detects the pilot flame and signals the gas valve to remain open. A weak or damaged thermocouple will cool and shut the gas valve, causing the pilot to go out. Thermocouples are relatively inexpensive and typically replaced by a technician or a confident DIYer.

Pilot Orifice And Tubing

Dirt, soot, or spider webs can clog the pilot orifice, reducing gas flow and causing instability. Cleaning with compressed air or careful brushes can restore flow, but replacement is recommended if corrosion is present.

Gas Control Valve

A malfunctioning gas control valve can cut gas supply to the pilot. Symptoms include the pilot not lighting despite gas flow or inconsistent flame. Valve replacement should be done by a licensed professional due to safety and code requirements.

Troubleshooting Checklist When Pilot Light Went Out On Furnace

Use this checklist to diagnose why the pilot light went out on a furnace. Work through items from simplest to more complex to avoid unnecessary repairs.

• Check For Gas Odor: If present, evacuate and call for help.
• Verify Gas Supply: Ensure the home gas supply is on and the furnace gas shutoff valve is open.
• Inspect For Drafts: Close nearby windows or doors and block drafts around the furnace area.
• Relight Per Manufacturer: Follow the safe relight procedure in the manual.
• Observe Flame: A weak, yellow, or flickering flame suggests dirty orifices or improper combustion air.
• Check Thermocouple: If the pilot lights but won’t stay lit, thermocouple replacement may be needed.
• Call A Technician: If electrical ignition problems, gas valve issues, or persistent outages occur.

When To Call A Professional

Call a licensed HVAC technician if any of the following apply: the pilot light went out repeatedly, there is a gas leak or strong odor, the pilot won’t stay lit after several safe relighting attempts, the gas control valve appears faulty, or the furnace shows combustion or venting issues.

Technicians can perform gas pressure checks, thermocouple and valve replacements, combustion analysis, and code-compliant repairs. For safety and insurance reasons, gas valve and regulator work is best left to professionals.

Preventive Maintenance To Reduce Pilot Light Problems

Regular maintenance reduces the chance the pilot light went out on a furnace and improves efficiency. Schedule annual professional inspections before the heating season for cleaning and safety checks.

• Replace or clean pilot orifices and burners as needed.
• Inspect and replace thermocouples and thermopiles if showing signs of wear.
• Seal drafts around doors, windows, and attic access to prevent gusts near the furnace.
• Keep the furnace area clear of dust and debris; change HVAC filters on schedule.

Energy-Efficient Alternatives And Modern Ignition Systems

Many modern furnaces no longer use a standing pilot light; they use electronic ignition systems that eliminate a continuously burning pilot. These systems improve safety and efficiency by lighting the burners only when heat is needed.

Converting an older furnace with repeated pilot problems to an electronic ignition or replacing it with a newer high-efficiency unit can reduce service costs and increase reliability. Consult an HVAC professional about retrofit options and cost-benefit analysis.

Cost Considerations When The Pilot Light Went Out On Furnace

Costs vary depending on the repair. Simple thermocouple replacement is often economical, while gas control valve replacement or full furnace replacement is more expensive. Typical ranges: thermocouple $75–$200 installed; gas valve $300–$800; new mid-efficiency furnace $2,500–$6,000 or more depending on size and features.

Homeowners should balance repair costs against furnace age and expected future repairs. If the furnace is over 15–20 years old with recurring issues, replacement may be more cost-effective.

Useful Safety Tips And Best Practices

• Never ignore a gas odor. Evacuate and call the gas company or 911.
• Follow the manufacturer’s relight instructions; improper relighting increases risk.
• Keep the furnace area ventilated and free of flammable materials.
• Install carbon monoxide detectors near sleeping areas and on each floor and test them monthly.
• Schedule annual professional tune-ups to catch problems before the pilot light goes out frequently.

FAQ: Quick Answers When The Pilot Light Went Out On Furnace

Why Did The Pilot Light Go Out Overnight?

Overnight drafts, a weak thermocouple, or a momentary interruption in gas pressure can cause the pilot to go out while the home is closed up and potentially colder.

Can A Homeowner Replace The Thermocouple?

Yes, a mechanically inclined homeowner can replace a thermocouple with the correct part and tools, but safety precautions and turning off gas are essential. When in doubt, hire a technician.

Is It Safe To Keep Relighting The Pilot?

Repeated relighting without resolving underlying causes is not advised. Persistent outages typically indicate a failing component or unsafe condition requiring professional attention.

How Long Should A Pilot Flame Burn?

A healthy pilot flame is steady and blue, extending a few millimeters around the thermocouple. A yellow or flickering flame indicates combustion or airflow problems that need service.

Additional Resources And Where To Find Help

For model-specific instructions, consult the furnace owner’s manual or the manufacturer’s website. For gas leaks or immediate safety concerns, contact the local gas utility or emergency services. For repairs, use licensed HVAC contractors with appropriate gas-fitting credentials and positive reviews.

Local utility companies often offer safety tips and may provide inspection programs. Homeowner insurance and warranty documentation may specify approved repair procedures and required licensed service for coverage.

Key Takeaway: When the pilot light went out on a furnace, prioritize safety, ventilate, check for gas odor, and follow safe relighting steps if appropriate; persistent problems, gas leaks, or valve issues require licensed professionals to ensure safe, code-compliant repairs and reliable heating.