The basic steps to relight your furnace pilot

If your furnace pilot light has gone out, you can relight it yourself in most cases. The process takes about five minutes and requires only a long lighter or long match — no tools. The steps are the same whether your furnace is in a basement, attic, or closet: locate the pilot light assembly, find the ignition button, and hold a flame to the pilot opening while pressing the button.

Before you start, turn off the furnace at the thermostat and wait five minutes. This clears any unburned gas from the chamber. Then locate the access panel on the front of the furnace — it usually slides or lifts off. Inside, you will see a small metal tube (the pilot burner) and a button labeled "Pilot" or "Ignition".

Key Takeaways

  • Turn off the furnace at the thermostat and wait five minutes before attempting to relight the pilot.
  • Hold a flame to the pilot opening while pressing and holding the ignition button for 30 to 60 seconds.
  • Once the pilot flame appears, release the button and watch for the flame to stay lit for at least one minute.
  • If the pilot will not stay lit after three attempts, the thermocouple may be faulty and you should contact a technician.

Finding the pilot light assembly and access panel

The access panel is usually on the front lower section of the furnace cabinet. On some models it slides out horizontally; on others it lifts straight up. If you cannot locate it, check the owner's manual or look for a diagram printed on the furnace itself — most manufacturers include one on the cabinet door or side.

Once the panel is open, you will see the pilot burner, which is a small brass or steel tube with a tiny opening at the end. Next to it or nearby is the ignition button, sometimes labeled "Reset" instead of "Pilot". Some furnaces also have a gas control knob with three positions: "Off", "Pilot", and "On". If yours has this knob, turn it to "Pilot" before you begin.

Lighting the pilot with a flame

Use a long lighter or long match — a regular match or lighter will not reach safely into the chamber. Hold the flame directly to the pilot opening (the small hole at the end of the pilot tube) while simultaneously pressing and holding the ignition button. Keep the button pressed for 30 to 60 seconds while the flame is present.

You should see a small blue flame appear at the pilot opening. Once it does, continue holding the button for another 10 to 15 seconds, then release it. The pilot flame should remain lit on its own. If it goes out when ready, wait a few seconds and repeat the process. Most pilots light on the second or third attempt.

What to do if the pilot stays lit

Once the pilot flame is burning steadily, turn the gas control knob (if your furnace has one) from "Pilot" to "On", or straightforward close the access panel and turn the furnace back on at the thermostat. The main burner should ignite within a few seconds. You will hear a whooshing sound as the larger flame comes to life.

Let the furnace run for a few minutes to make sure it stays on. Check that warm air is flowing from the vents. If the furnace shuts off again within the next hour, the thermocouple may be failing, and you should contact a technician rather than attempt further relighting.

When the pilot will not stay lit

If the pilot light goes out when ready after you release the button, or if it will not light at all after three attempts, the problem is usually a faulty thermocouple. This is a safety device that detects whether the pilot flame is burning; if it fails, the furnace will not allow gas to flow to the pilot. Replacing a thermocouple requires opening the furnace further and is best left to a technician.

Another common cause is a clogged pilot opening. If you see the flame trying to light but it is very weak or off to one side, the opening may be blocked by dust or debris. You can try gently cleaning it with a thin wire or needle, but be careful not to damage the tube. If cleaning does not help, contact a technician.

Safety precautions while relighting

Never force the ignition button or hold it down for more than 60 seconds at a time. Holding it longer can flood the chamber with gas, which is a fire hazard. If you smell gas while working on the furnace, stop when ready, close the access panel, and open windows to ventilate the room. Do not attempt to relight if you smell gas — call your gas company's emergency line instead.

Make sure the furnace is off at the thermostat before you open the access panel. Do not relight the pilot if anyone in your home has a gas detector alarm going off. Wait for the alarm to clear and for a technician to inspect the furnace before trying again.

When to call a technician instead

If the pilot light goes out repeatedly over several days or weeks, the furnace has a deeper problem that relighting will not fix. Common causes include a failing thermocouple, a gas valve that is not holding pressure, or a draft that is blowing out the pilot flame. A technician can diagnose which one and repair it.

You should also call a technician if you cannot locate the pilot light assembly, if the access panel is stuck or damaged, or if you are uncomfortable working inside the furnace at all. A service call typically costs between $100 and $200, but it is worth the cost if you are unsure about what you are doing.

Frequently Asked Questions

How long should I hold the ignition button down?

Hold the button for 30 to 60 seconds while the flame is touching the pilot opening. Once you see the pilot flame appear, continue holding for another 10 to 15 seconds, then release. If the flame goes out right away, wait a few seconds and try again.

What does the pilot flame look like?

A healthy pilot flame is small, blue, and steady — about the size of a pencil tip. It should not flicker or lean to one side. If the flame is yellow or orange, the pilot opening may be dirty, and you should have a technician clean it.

Is it safe to relight the pilot myself?

Yes, relighting a pilot is a safe task if you follow the steps and wait five minutes before starting. The main risk is holding the ignition button too long, which can flood the chamber with gas. If you smell gas at any point, stop and ventilate the room.

Why does my pilot light keep going out?

A pilot that goes out repeatedly usually has a faulty thermocouple, a gas valve problem, or a draft blowing it out. Relighting it temporarily will work, but the furnace needs a technician to find and fix the underlying cause.

Can I use a regular match or lighter instead of a long one?

A long lighter or long match is much safer because it keeps your hand farther from the pilot opening and the hot furnace. A regular match or lighter will not reach far enough into the chamber without risking a burn.