How to relight a pilot light: check for gas first, then follow the label
Many older furnaces have a standing pilot you can relight in a few minutes. The first step is not the match: it is your nose.
Check for gas before you touch anything
If you smell gas, stop. Do not look for the source, do not flip a switch and do not light anything. Leave the house and call your gas utility or 911 from outside. A pilot light that has been out for a while can let unburned gas collect, and that is the case where this job turns dangerous.
No smell? Then you can go on. Only a furnace with a standing pilot is a candidate here.
Does your furnace have a pilot light at all?
Most furnaces built in the last couple of decades use an electronic igniter, not a flame that burns all day. There is no pilot to relight on those. If your furnace clicks, glows or sparks before the burners start, it is an electronic system, and a dead igniter is a service call.
| What you see | What it means |
|---|---|
| Small steady flame, visible at all times | Standing pilot: relighting may be an option |
| Glowing element or clicking before the burners | Electronic ignition: no pilot to light |
| Gas smell at any point | Stop, leave, call the gas utility or 911 |
The general steps for a standing pilot
Your furnace has a label, usually on the inside of the access panel, with the exact steps for that model. Follow that label over anything written here. The usual order looks like this.
- Set the thermostat to its lowest setting or to off.
- Turn the gas control knob to the off position and wait at least five minutes so any gas can clear. Smell again. If you pick up gas, leave and call.
- Turn the knob to the pilot position, press and hold the reset or pilot button, and light the pilot with the long lighter the label calls for.
- Keep holding the button for the time the label states, then let go. The pilot should stay lit.
- Turn the knob to on, put the access panel back and raise the thermostat.
Take it slowly. Rushing the wait is the commonest mistake.
Do not keep trying if it will not stay lit
One or two careful tries is fine. If the flame goes out as soon as you release the button, stop. That points to a worn thermocouple, a dirty pilot or a draft problem, and none of those are a homeowner repair. Our guide to a pilot light that won't stay lit explains the pattern.
Do not bypass the safety valve, wedge the button or hold it past the label's time. Those parts exist to cut the gas when the flame is gone.
When to call a technician instead
Call a licensed HVAC technician if there is any gas smell, if the pilot will not stay lit, if the flame is yellow or flickering, if you cannot find the label, or if you are simply not sure. A carbon monoxide detector on each level is your backstop. If it sounds, leave the house and call 911 from outside.
Frequently asked questions
Is it safe to relight a pilot light myself?
On a standing-pilot furnace it can be, if there is no gas smell and you follow the label on your furnace exactly. If you smell gas, leave and call your gas utility or 911.
How long should I wait before relighting a pilot light?
Wait at least five minutes after turning the gas control off, or longer if your label says so. That lets any gas clear before you light the pilot.
Why won't my pilot light stay lit after I relight it?
Common causes are a worn thermocouple, a dirty pilot or a draft. Those need a licensed technician, so stop after one or two careful tries.
My furnace has no pilot light. What now?
Most newer furnaces use an electronic igniter. There is nothing to relight, so a furnace that will not start needs a technician to check the igniter.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- ENERGY STAR. Furnaces
- CDC. Carbon Monoxide Poisoning Basics