If you’ve ever dealt with a furnace that won’t stay on, you know the frustration. Many times, the problem comes down to one small but crucial part: the furnace pilot light. When it keeps going out, you’re left without heat right when you need it most. As someone who works on furnaces every day during heating season, I can tell you this is one of the most common issues homeowners call about. The good news? Once you understand the causes, you can often spot the signs early and get it fixed before you’re left in the cold.
What Is a Furnace Pilot Light?
The furnace pilot light is a tiny flame that stays lit inside your furnace. Its job is simple: ignite the main burners when your thermostat tells the system to turn on. If that flame won’t stay lit, the burners can’t fire up. No flame, no heat.
(Think of it like your stove. If the burner won’t ignite, you’re not cooking dinner. Same deal here, just a lot colder if it fails.)
Common Reasons the Furnace Pilot Light Goes Out
Dirty Pilot Tube
Over time, dust and soot can clog the small opening where the pilot flame sits. A blocked tube makes it hard for gas to flow properly, so the flame goes out. Sometimes you’ll see the flame flicker weakly before dying.
Faulty Thermocouple
The thermocouple is a safety device that senses the pilot flame. If it doesn’t detect heat, it shuts off the gas to prevent leaks. When the thermocouple goes bad or gets dirty, it can “think” the flame isn’t there and cut the gas, even when the flame is burning.
(Yes, it’s overly cautious. But trust me, you want it shutting off gas when there’s no flame.)
Drafts or Ventilation Issues
Sometimes the problem isn’t inside the furnace at all. A strong draft or poor ventilation can blow out the furnace pilot light. This can happen in older homes where the furnace is near a drafty door or window.
Gas Supply Problems
Low gas pressure or a faulty gas valve can also cause the flame to go out. If your other gas appliances are acting up too, this may be the culprit.
How Technicians Diagnose the Problem
At Sub Zero Temp Control, we take a step-by-step approach to figure out why the furnace pilot light won’t stay lit. We check the pilot tube, test the thermocouple, look for drafts, and confirm the gas supply. That way, nothing gets overlooked before we move on to repairs.
Can You Relight the Furnace Pilot Light Yourself?
In many cases, yes. Most furnaces have instructions right on the panel. You’ll typically:
-
Turn the gas knob to “off.”
-
Wait a few minutes for gas to clear.
-
Switch to “pilot,” press the reset button, and light the flame with a match or igniter.
-
Hold the button for 30–60 seconds, then release.
If the flame stays lit, great. If it goes out again right away, that’s a sign of a bigger issue. Don’t keep relighting it over and over — call a pro before you wear out your patience (and the lighter).
When It’s Time to Call a Professional
Relighting is one thing. Replacing a thermocouple, cleaning a blocked tube, or repairing gas valves is another. These jobs require tools, training, and sometimes special parts. That’s why scheduling professional heating repair with Sub Zero Temp Control makes all the difference.
When a Replacement Makes More Sense
If an older unit has recurring furnace pilot light problems, repair may not be the best long-term move. The U.S. Department of Energy explains that modern furnaces use electronic ignition (no standing pilot) and offer higher efficiency. If your system is aging or facing multiple issues, furnace replacement could be the smarter move.
Preventing Future Pilot Light Problems
Regular maintenance goes a long way. Changing filters, keeping the area around the furnace clean, and scheduling seasonal tune-ups all help. According to ENERGY STAR’s maintenance checklist, routine care not only improves efficiency but also extends the life of your system.
I can tell you from experience — most of the pilot light issues I see could’ve been prevented with a little upkeep. Skipping maintenance is kind of like skipping dentist checkups — everything seems fine until it suddenly isn’t.
Final Thoughts on the Furnace Pilot Light
The furnace pilot light may be small, but it plays a huge role in keeping your home warm. When it keeps going out, the cause is usually dirty components, a faulty thermocouple, drafts, or gas supply problems. Relighting is sometimes simple, but repeated failures mean it’s time to call a professional.
At Sub Zero Temp Control, we’re here to help homeowners across Vancouver, WA, and the surrounding areas with furnace repairs, maintenance, and replacements. Contact us today to schedule service and get your home comfortable again before the next cold snap hits.
