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Furnace Pilot Light Out? What to Know Before You Relight It

Updated November 2, 2026 · General information, not HVAC or gas-fitting advice

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Gas smell, hissing, or a carbon monoxide alarm sounding? Stop reading and get out. Do not turn anything on or off and do not look for the cause. From outside, call 911 and your gas utility. Go back in only when responders say it is safe. Gas smell steps · CO alarm steps

The short answer: Only furnaces with a standing pilot can be relit this way. If you smell gas or hear hissing, leave and call your gas utility from outside. If you see no PILOT or ON/OFF control, stop. If the pilot will not stay lit after careful attempts, or the flame is yellow or sooty, turn the furnace off and call a licensed technician.

Safety first. Gas, burners, venting and wiring are jobs for a licensed HVAC professional. This page covers only checks a homeowner can do without opening the furnace or touching gas parts.

Is there a pilot at all?

Minnesota Commerce says high-efficiency furnaces use electronic ignition rather than a pilot flame. Budget Heating, an HVAC contractor, says: "If you do not see a PILOT or ON/OFF control, stop. Do not attempt a manual relight." Many newer furnaces have no pilot. Your furnace's label and manual come first.

Before you start

If you smell gas or hear hissing, evacuate and call your gas utility from outside (Budget Heating). Follow the gas smell steps.
Turn the thermostat off and the furnace gas control to OFF, then wait 3 to 5 minutes. Budget Heating says that lets unburned gas dissipate.
Connecticut PURA says never to turn the gas back on once it has been shut off for a safety concern. Budget Heating adds that after a meter shutoff or utility work, the utility or local code may require a qualified technician to restore service or relight appliances.

The steps in outline (Budget Heating)

At the gas valve, turn the knob from OFF to PILOT as shown on the appliance label.
Press and hold the pilot or reset button. Light the pilot with a long lighter or match. Some systems spark automatically.
Keep holding for 30 to 60 seconds so the thermocouple or thermopile heats up.
Release slowly. A steady blue flame is the goal. If it stays lit, turn the knob to ON and restore power.

This is a summary of one contractor's instructions, not your furnace's. Your label's steps win if they differ.

Stop and call a pro if

The pilot won't stay lit after careful attempts, controls are stiff, you smell gas, or the pilot goes out repeatedly (Budget Heating).
The flame is yellow or sooty. Budget Heating: turn the furnace off and call a licensed technician.
Thermocouple replacement, gas line or valve repair, and combustion analysis are professional-only (Budget Heating).

No carbon monoxide alarm yet?

CPSC and the NFPA say to have alarms on every level and outside sleeping areas. Look for a UL listing and read the label.

CO and your furnace See carbon monoxide alarms

Checks did not fix it?

Gas, burner, ignition and venting problems are for a licensed HVAC technician. Our guide covers which signs mean call now.

When to call an HVAC technician Find a licensed HVAC pro near you

Common questions

Do all furnaces have a pilot light?

No. Minnesota Commerce says high-efficiency furnaces use electronic ignition rather than a pilot flame.

How long do I wait before relighting?

Budget Heating says to turn the gas control to OFF and wait 3 to 5 minutes. Follow your own furnace's label if it says otherwise.

What if the pilot keeps going out?

Stop and call a licensed technician. Budget Heating lists a pilot that won't stay lit or goes out repeatedly as a reason to stop.

Related guides

Sources