How Do I Manually Light My Furnace Pilot Light?

If you have an older furnace, you may be wondering how do I manually light my furnace pilot light when your heat suddenly stops working. Many older furnace models use a gas furnace pilot light—a small blue flame that ignites the burners and keeps your system running. When that pilot light goes out, the gas supply is interrupted and warm air can’t circulate through your home.

Unlike systems with electronic spark ignition, these furnaces require manual relighting using the gas valve and gas valve control knob. Until that small blue flame is restored, your heating system won’t function, leaving your home cold and uncomfortable.

Understanding how pilot lights work, why they go out, and how to safely relight the pilot is essential for anyone with older gas appliances. Let’s walk through the basics.

What Is a Furnace Pilot Light?

A furnace pilot light is a small flame that’s constantly burning inside older gas furnaces. This flame works to ignite the main burners whenever the thermostat gets adjusted or sends a signal for more heat. If the flame goes out, the furnace cannot run. That’s why knowing the answer to “How do I manually light my furnace pilot light?” is such a helpful trick for owners of older systems.

How Do You Manually Light a Furnace Pilot Light in 7 Steps

Before you begin, make sure your furnace is completely turned off and that you’re working in a well-ventilated area.

Manually lighting a furnace pilot light is a straightforward process on older systems, but following each step carefully is important for both safety and proper operation:

Step by step: How To Manually Light a Furnace Pilot Light

1. Turn the furnace off

Locate the gas control knob near the bottom of the furnace and turn it to OFF. Wait at least 5 minutes to allow any excess gas to clear.

2. Locate the pilot light opening

Find the pilot tube and burner assembly near the gas valve. Use a flashlight if needed to clearly see the opening.

3. Set the knob to PILOT

Turn the gas valve control knob to PILOT and press it down to allow gas to flow.

4. Light the pilot flame

While holding the knob down, press the ignition button or use a long match or lighter to ignite the pilot. You should see a small blue flame.

5. Hold the knob to stabilize the flame

Keep holding the knob down for 20–30 seconds so the thermocouple can heat up and keep the flame lit.

6. Turn the furnace back on

Release the knob slowly, confirm the pilot stays lit, then turn the control knob to ON and adjust the thermostat.

7. Check that the system is running properly

Listen for the burners to ignite and confirm warm air is coming from the vents.

 

Common Pilot Light Troubleshooting for Gas Furnaces

If your furnace pilot light doesn’t stay lit or the furnace won’t turn on after following the steps above, a few common issues may be the cause.

• Pilot light won’t stay lit: This is often due to a dirty or faulty thermocouple that can’t sense the flame properly.
• No gas flow to the pilot: Check that the gas valve control knob is fully set to PILOT or ON and that the gas supply to the furnace hasn’t been shut off.
• Pilot flame is weak or yellow: A weak flame may indicate dirt or debris in the pilot tube, which can prevent proper ignition.
• Furnace won’t ignite after pilot is lit: The issue may be with the gas valve, thermostat, or internal furnace components.
• Strong gas smell: Turn the furnace off immediately, ventilate the area, and contact a professional. Do not attempt to relight the pilot.

Do All Gas Furnaces Have Pilot Lights?

No. Modern gas furnaces typically use an electronic ignition system vs a standing pilot flame. Many older furnaces and some water heater designs will still use traditional pilot lights, but these are usually models made before 2010. If you’re not sure which type you have, check your owner’s manual. You can also take a look at the pilot control panel or the access door on the furnace.

Why Did My Pilot Light Go Out?

Pilot lights can go out for several reasons. Sometimes there may have been a draft near the exhaust pipe. Other times there may have been temporary disruptions in gas flow. Having a dirty flame sensor or a weak flame because of a partially blocked gas line are common causes too. There are all kinds of failures that can pop up. Maybe it’s a failing thermocouple, basic dust buildup, or even issues with natural gas supply. All of these can extinguish the flame.

How Do I Know If My Pilot Light Is Out?

You can usually tell your pilot light is out if your furnace stops producing heat. Of course, there are lots of reasons why your system might stop working. One sure way to know what’s going on is to check to see whether there’s a small bright blue flame through the access door. If the flame is completely gone, then being able to manually light the furnace pilot light can get things back on track to restore heating.

Can You Light a Furnace Pilot Light With a Lighter?

Yes—if your furnace doesn’t have a built-in igniter, you can use a long-handled lighter to light the pilot. Just refer to your user’s manual before attempting this step, and always practice safety. You’ll want to be sure to allow time for any accumulated gas to dissipate. You’ll also want to avoid leaning directly into the pilot light opening. Using a light to get your pilot light back is relatively simple, but you should never attempt this if you suspect a gas leak.

Where Is the Pilot Light Opening Located on My Furnace?

The pilot opening is typically found behind the lower access door. You’ll find this near the gas pipe and burner assembly. You may also see the pilot control panel, which includes the gas control knob and ignition instructions. If you can’t locate it, check out your owner’s manual. There might also be some helpful labels printed inside the access panel.

Can You Relight a Furnace by Yourself?

Most homeowners with older models can safely relight the pilot if they work carefully. Knowing how to manually light a furnace pilot light is definitely useful, especially during cold weather when the flame may go out due to drafts.

When Should I Call a Professional HVAC Technician?

Sometimes you may not want to work on the pilot light yourself. Other times, there are other signs of trouble that can require extra help. You’ll want to call a professional HVAC technician, for example, if you smell gas or suspect a gas leak. They’ll be able to help you pinpoint the issue. Another situation where you might need professional help is if the flame appears yellow or weak instead of bright blue. They’ll help you get the flame back to its right force.

If you can’t get the pilot to stay lit on your own, that’s another reason to call for help. There’s a chance that something has gone wrong with the gas supply where it doesn’t seem to reach the pilot opening. Or in general, if you feel unsure about any part of the relighting process, just bring in a professional. Safety always comes first when working with gas furnaces and gas appliances.

What Do I Do If My Pilot Light Won't Stay Lit?

If the pilot won’t stay lit after following the main steps for how do I manually light my furnace pilot light, the problem might be as simple as a dirty flame sensor. Other problems could be a worn thermocouple or the trouble of restricted gas flow. There could also be debris near the pilot opening that’s causing a weak flame. This is why it’s nice to have professionals available to help. In some cases, the ignition system or gas line may require furnace repair.

How Do I Force My Furnace to Start After Relighting the Pilot?

Once you successfully relight the pilot, turn the gas control knob back to ON and close the access door. After this, set your thermostat for heat. If the burners do not ignite within a few minutes, there may be a deeper issue within the furnace, in which case, you’ll need to reach out for professional inspection.

How Can I Prevent My Pilot Light From Going Out Again?

You obviously want to keep warm when the weather is cold outside, so always be sure to keep the pilot light opening clean and free of dust. You’ll also want to confirm that the airflow around the furnace isn’t causing drafts.

Having the flame sensor cleaned annually can be a big help for older systems. A service professional can also work to inspect the gas line and gas supply for consistency. Maintaining your system is key, but knowing how to manually light a furnace pilot light is also useful!

If you keep running into problems with your older system, it might be time for an upgrade. You can count on Surplus City for energy-efficient furnaces with all of today’s best models. We offer low prices because we source directly from the manufacturers. Sometimes all it takes is a simple cleanup to get your pilot light working like it should, but if there are other problems happening we can get you set up with great savings on a new system!