If you’re relighting your furnace’s pilot light more than once, something specific is causing it — pilot lights don’t go out randomly. Here’s what to check.
Relighting the pilot more than twice isn’t a fix — it’s a sign something specific has failed. A furnace repair visit finds it instead of patching it every few days.
1. A Weak or Failing Thermocouple
The thermocouple is a small safety sensor that detects the pilot flame and keeps the gas valve open. When it wears out, it can falsely signal that the flame is out, shutting off the gas supply and extinguishing the pilot — even though the flame was actually fine. This is the single most common cause and a straightforward, inexpensive repair.
2. A Draft Blowing Out the Flame
Pilot lights sit in an open area and can be blown out by a draft from a nearby door, window, or even airflow from the furnace’s own blower compartment if a panel is loose or missing.
Check it yourself: Make sure furnace access panels are fully seated and latched — they’re often part of the safety circuit as well as a draft shield.
3. A Dirty Pilot Orifice
Dust and debris can partially clog the small opening the pilot gas flows through, causing a weak, unstable flame that flickers out easily. This shows up as a small, sputtering flame instead of a strong blue one.
4. Excess Air in the Gas Line
After any service to the gas line — including a service visit — air can be temporarily in the line, causing an unstable pilot for the first several attempts to light it. This should resolve after a few tries; if it doesn’t, something else is wrong.
5. A Failing Gas Valve
Less common, but if the thermocouple tests fine and drafts are ruled out, the gas valve itself may be intermittently restricting gas flow to the pilot.
When to Stop DIY-ing It
If you’ve relit the pilot more than two or three times and it keeps going out, stop trying and call — repeated manual relighting isn’t a long-term fix, and gas components should be diagnosed by a technician.