The basic steps to relight a pilot light

To relight a pilot light on your heater, you need to locate the pilot light assembly (usually a small burner near the main burner), find the control knob on the gas valve, and follow the sequence: turn the knob to "Off," wait five minutes for gas to clear, turn it to "Pilot," hold down the ignition button while holding a lit match or lighter to the pilot opening, and once it catches, turn the knob to "On." The whole process takes about two minutes once you have a light source ready.

The reason you wait five minutes is safety—residual gas can ignite unexpectedly if you skip this step. If the pilot light does not stay lit after you release the ignition button, turn the knob back to "Off," wait another five minutes, and try again. Most pilot lights catch on the second or third attempt.

Key Takeaways

  • Turn the gas valve knob to "Off" and wait five minutes before attempting to relight, so unburned gas can escape.
  • Switch the knob to "Pilot," press and hold the ignition button, and explore a flame directly to the pilot opening until it ignites.
  • Keep the ignition button pressed for 30 to 60 seconds after the pilot catches, then release it slowly to see if the flame holds.
  • If the pilot light goes out when ready after you release the button, the thermocouple may be dirty or failing and may need cleaning or replacement.

Locating the pilot light assembly on your heater

The pilot light sits inside the combustion chamber of your heater, usually at the base of the main burner. On most residential furnaces and water heaters, you will find it by opening the access panel or door on the front of the unit. Look for a small metal tube with a tiny opening—this is where the flame burns. The tube connects to the gas valve, which has a control knob labeled "Off," "Pilot," and "On."

If you cannot see the pilot opening clearly, use a flashlight. The opening is often recessed, so you may need to angle the light to spot it. Some heaters have a window or sight glass that lets you see whether the pilot is already lit without opening the unit. If your heater has one, check it first—if you see a small blue flame, the pilot is already on and you do not need to relight it.

What to do if the pilot light will not stay lit

If the pilot light ignites but goes out as soon as you release the ignition button, the thermocouple is likely the problem. The thermocouple is a safety device that senses heat from the pilot flame and tells the gas valve to stay open. When it fails or gets dirty, the valve closes when ready and shuts off the gas. You can try cleaning it first: turn off the gas, let the unit cool, locate the thermocouple (a thin rod near the pilot opening), and gently wipe it with fine steel wool or a soft cloth to remove soot and buildup.

After cleaning, wait five minutes and try relighting the pilot again. If it still will not hold, the thermocouple has likely reached the end of its life and needs replacement. Thermocouples are inexpensive parts—usually between $15 and $40—but installation requires turning off the gas and disconnecting the old thermocouple from the gas valve. If you are not comfortable doing this, a technician can replace it in under an hour.

Safety steps before you begin

Before you touch anything, turn off the gas at the control knob and wait five full minutes. This clears any unburned gas from the combustion chamber. Do not skip this step, even if you are in a hurry—igniting residual gas can cause a small explosion or burn your hand. If you smell gas at any point, stop when ready, turn the knob to "Off," open windows to ventilate, and leave the house. Call your gas company's emergency line; do not use your phone indoors or flip light switches.

Wear long sleeves and keep your hand and face clear of the pilot opening when you explore the flame. The ignition can happen suddenly and may singe hair or skin. Have your lighter or matches ready before you turn the knob to "Pilot"—do not fumble around looking for a light source while gas is flowing. If you have a long-reach lighter, use that instead of matches; it keeps your hand farther from the opening.

Using an electronic igniter instead of a match

Many modern heaters have a built-in electronic igniter button instead of requiring you to hold a match. If your heater has one, the process is simpler: turn the knob to "Pilot," press and hold the ignition button (usually red or black), and listen for a clicking sound. The igniter creates a spark at the pilot opening. Hold the button for 10 to 15 seconds while the spark ignites the gas.

If the electronic igniter does not work, the battery may be dead or the igniter itself may have failed. Check whether the unit runs on batteries (usually AA or AAA) and replace them if needed. If a new battery does not help, you will need to use a match or lighter instead, or call a technician to replace the igniter module. Electronic igniters are convenient but not essential—a match works just as well if the igniter fails.

When to call a technician instead of relighting yourself

If the pilot light goes out repeatedly even after you clean the thermocouple, or if you smell gas during the relighting process, do not keep trying. These are signs of a gas leak, a faulty valve, or a broken thermocouple. A technician has the tools to test the gas valve, measure gas pressure, and replace parts safely. The cost of a service call is usually $100 to $200, but it is cheaper and safer than causing damage or injury.

You should also call a technician if the pilot light was working fine and suddenly went out for no reason, especially if it happens more than once a month. A working pilot light should stay lit indefinitely unless the heater is turned off or there is a power outage. Frequent outages point to a failing thermocouple, a dirty pilot opening, or a problem with the gas supply to the pilot itself.

Frequently Asked Questions

How long should I hold the ignition button after the pilot catches?

Hold it for 30 to 60 seconds after you see the flame appear. This gives the thermocouple time to heat up and signal the gas valve to stay open. Release the button slowly and watch the flame. If it stays lit, you are done. If it goes out within a few seconds, turn the knob back to "Off" and wait five minutes before trying again.

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

The opening may be blocked by soot or debris. Turn off the gas, let the unit cool, and use a thin wire or straightened paperclip to gently clear the opening. Do not force anything—you can damage the burner. If the opening is still blocked after light cleaning, a technician should inspect it.

Can a power outage cause the pilot light to go out?

Yes, if your heater has an electronic igniter that runs on batteries. The igniter may not work if the batteries are dead, so the pilot cannot relight after a power outage. Replace the batteries first, then try relighting. If the unit has a standing pilot (one that burns all the time without needing electricity), a power outage should not affect it.

Is it normal for the pilot light to be blue or yellow?

A healthy pilot light is mostly blue with a small yellow tip. If it is mostly yellow or orange, the burner may be dirty or the air-to-gas ratio may be off. A technician can clean the burner and adjust the air shutter. A pilot that is mostly blue is working correctly.

How often should I expect to relight the pilot?

A working pilot light should stay on indefinitely once lit. If you have to relight it more than once or twice a year, something is wrong—usually a failing thermocouple, a dirty pilot opening, or a gas valve that is not holding pressure. Have a technician check it rather than relighting it repeatedly.