The basic steps to relight a pilot light

Restarting a furnace pilot light usually takes five to ten minutes and requires no tools beyond a long lighter or long match. The process is the same on most furnaces: locate the pilot light assembly (a small opening near the bottom of the furnace), turn the gas control knob to "Pilot," hold down the ignition button while you light the pilot flame with your lighter, and hold the button for 30 to 60 seconds after the flame appears. Once you release the button and the flame stays lit, turn the gas control knob back to "On" and the furnace should resume heating.

The hardest part is usually finding the pilot light itself. On most furnaces it sits inside a small metal tube or chamber near the bottom of the unit. You may need to remove a front panel or access cover to see it clearly. If your furnace has a piezo igniter (a button you push to create a spark), you can use that instead of a lighter—push it repeatedly while holding the gas knob on "Pilot" until the flame catches.

Key Takeaways

  • Turn the gas control knob to "Pilot," hold the ignition button, and light the pilot opening with a long lighter or match while holding the button down for 30 to 60 seconds.
  • If the pilot light goes out when ready after you release the button, the thermocouple (a safety sensor) may be dirty or failing, and you should call a technician.
  • If you smell gas but cannot see a flame, or if the pilot light will not stay lit after three attempts, stop trying and call a heating professional—do not force the ignition.
  • Most pilot lights stay lit indefinitely once restarted; if yours goes out repeatedly, the problem is not the restart process but a component that needs replacement.
  • Never use a regular match or lighter if you cannot reach the pilot opening safely—a long lighter designed for fireplaces is worth buying if you plan to do this yourself.

Finding the pilot light assembly on your furnace

The pilot light sits in a small metal tube or chamber, usually near the bottom front of the furnace. On most units, you will see a control panel with three knobs: one labeled "On/Off," one labeled "Pilot/On," and sometimes a third for temperature. The pilot assembly is typically just below or to the side of these knobs. If your furnace has a front cover or access panel, you may need to remove it first—usually two or three screws hold it in place.

Look for a small opening about the size of a pencil eraser where the pilot flame should be visible. If the furnace is cold and dark inside, use a flashlight to see into the chamber. Some furnaces have a window or sight glass so you can see the pilot without opening the unit. If you cannot locate the pilot light after checking the front and sides of the furnace, consult your furnace manual or take a photo of the model number and search online for a diagram—different manufacturers place it in slightly different spots.

What to do if the pilot light will not stay lit

If the pilot flame appears when you light it but goes out as soon as you release the ignition button, the problem is almost always the thermocouple, a small safety sensor that sits in the pilot flame. The thermocouple detects whether the pilot is burning and tells the gas valve to stay open; if it is dirty or failing, the valve closes when ready. You can try cleaning it yourself by gently rubbing the tip of the thermocouple with a soft cloth or fine sandpaper, but if the flame still goes out after relighting, the thermocouple needs replacement and you should call a heating technician.

If the pilot light stays lit for a few seconds but then goes out, or if it lights and goes out repeatedly over several hours, the problem may be a draft blowing out the flame, a clogged pilot opening, or a failing thermocouple. Do not keep relighting it—each failed attempt wastes gas. Call a professional instead. If you smell gas but see no flame, or if you smell gas and cannot relight the pilot after one careful attempt, turn off the furnace, leave the house, and call your gas company or a technician from outside.

Safety steps before you start

Before you touch anything on the furnace, make sure the area around it is clear of clutter and that you have good light. If you cannot see the pilot light opening clearly, do not attempt to light it—use a flashlight or wait until daylight. Keep the long lighter or match away from loose clothing, hair, or anything flammable. If you have a gas smell anywhere in your home, do not attempt to relight the pilot; instead, leave the house and call your gas company when ready.

If your furnace has a piezo igniter, test it before you try to use it—press the button a few times to make sure it creates a visible spark. If it does not spark, use a long lighter instead. Never use a regular match or short lighter; you risk burning your hand or arm reaching into the furnace chamber. If you are uncomfortable working near the furnace or cannot safely reach the pilot light, call a technician—the cost of a service call is far less than the cost of a burn injury or a gas leak.

When to call a heating professional instead

If the pilot light will not stay lit after you have relit it once or twice, or if it goes out repeatedly within hours or days, do not keep trying to restart it yourself. A pilot light that will not hold a flame points to a failing thermocouple, a clogged pilot opening, a problem with the gas valve, or a draft issue—all of which require a technician to diagnose and fix. Continuing to relight it wastes gas and delays the repair.

You should also call a professional if you smell gas anywhere in your home, if you see no flame when you attempt to light the pilot, if you hear a hissing sound from the furnace, or if the furnace does not heat the house even after the pilot is relit. These are signs of a gas leak, a broken component, or a safety issue that needs when ready attention. A heating technician can inspect the furnace, test the thermocouple and gas valve, and replace any worn parts in under an hour.

How to prevent the pilot light from going out

Once the pilot light is relit and burning steadily, it should stay lit indefinitely unless something goes wrong. The most common reason a pilot light goes out is a failing thermocouple, which typically lasts five to ten years. If your furnace is older than that and the pilot has recently started going out on its own, the thermocouple is probably near the end of its life and should be replaced before it fails completely.

Drafts can also blow out a pilot light, especially if your furnace is in a basement near a door or window. If the pilot keeps going out on windy days or after you open a nearby door, check whether the furnace room has adequate ventilation and whether the furnace access panel is sealed properly. A heating technician can also install a draft shield around the pilot light if drafts are a recurring problem. Beyond that, there is little you can do to prevent a pilot light from going out—it is a sign that a component needs attention, not a sign of poor maintenance.

Frequently Asked Questions

How long should I hold the ignition button down?

Hold it for 30 to 60 seconds after the flame appears. This gives the thermocouple time to heat up and signal the gas valve to stay open. If you release the button too soon, the flame will go out. If the flame is still not holding after 60 seconds, release the button and wait a few minutes before trying again.

What if I cannot see the pilot light even with a flashlight?

The opening may be blocked by dust or debris. Turn off the furnace, wait for it to cool, and use a thin wire or straightened paperclip to gently clear the opening. Do not force anything into it. If you still cannot see the pilot after clearing it, or if you are not comfortable doing this, call a technician.

Is it normal for the pilot light to go out in winter?

No. A pilot light should stay lit all season once it is relit. If it goes out during winter when the furnace is running regularly, the thermocouple is likely failing or there is a draft problem. Call a technician to inspect it rather than relighting it repeatedly.

Can I relight the pilot if I smell a little gas?

A faint gas smell near the furnace is normal when the pilot is out, because gas is flowing to the pilot opening. If the smell is strong, fills the room, or comes from elsewhere in your home, do not attempt to relight the pilot. Leave the house and call your gas company or a technician from outside.

How much does it cost to have a technician relight the pilot?

Service call costs vary by location and company, typically ranging from $75 to $150 for a technician to come out and relight the pilot. If the thermocouple or another part needs replacement, the total cost will be higher. Many heating companies offer annual maintenance plans that cover pilot light issues at no extra charge.