5 Reasons Why Your Pilot Light Keeps Going Out

Troubleshooting Problems with your Furnace Pilot Light

Here's Why Your Furnace Pilot Light Keeps Blowing Out

  1. The thermocouple is bad. More >>
  2. The pilot orifice is dirty. More >>
  3. The gas regulator is bad. More >>
  4. Gas availability is fluctuating. More >>
  5. A draft is blowing the pilot out. More >>

You awake on a cold winter morning and cast the covers aside. A fierce, freezing draft sends shivers down your spine. Something's wrong. The furnace stopped working at some point during the night.

Attempts to re-light the pilot light are futile. It won't stay on. Maybe the pilot stays on for a moment and the furnace attempts to fire, but almost immediately shuts down. Why does this happen?

Before conceding the cost of emergency repairs and calling an HVAC professional, read ahead for some of the most common reasons why your furnace pilot light won’t stay on. You may be able to fix the problem on your own if you’ve got the tools and the wherewithal.

Please fix my furnace RIGHT NOW!

Of course, if you want to make sure the job is done right with the least amount of risk, contact experienced professionals at Hot Point for furnace repairs ASAP.

1) Faulty Thermocouple

If your pilot light won’t stay lit, the thermocouple is very likely the culprit.

Gas furnace with bad thermocouple

Pilot light won't stay on? Read on for reasons why, and what you can do to fix it.

The thermocouple is the copper rod the pilot flame directly hits. Sometimes it's referred to as the "flame sensor." It's a safety mechanism that shuts the gas off should the pilot go out. If the thermocouple fails to shut off the gas, all the gas flowing through the furnace could get into your home. The thermocouple safeguards against a catastrophic buildup of gas.

DIY Fix - How to Locate the Thermocouple

First off, grab a flashlight and a screwdriver before inspecting your furnace. You'll have to remove the cover, and chances are the lighting won't be working in your favor. The only thing more frustrating than a busted furnace is the hundred trips to the garage for tools when you're trying to fix it.

For safety's sake, shut off power to the furnace by switching the breaker to the off position, and close the gas valve.

The thermocouple isn't too difficult to find. Locate the pilot light and look for the tip of a copper rod very nearby. That's the thermocouple.

Can't Find the Pilot Light?

If you're having trouble locating the pilot or thermocouple, double-check to make sure your unit actually has a standing pilot light. Standing pilot lights are common in older furnaces, but many newer furnaces have intermittent pilot lights or hot surface igniters. In these systems, the pilot will only light (in the case of hot surface igniters, the igniter surface heats) when the thermostat makes a command for heat.

No matter the pilot configuration, the thermocouple will be near the burners—look for a removable metal rod nearby.

Thermocouple on a gas furnace

Locate the copper rod near the burners. This is the thermocouple.

Thermocouple behind furnace burners

If you look very closely, you'll find the thermocouple tucked in behind the burners.

Why the Thermocouple Fails

The thermocouple needs to detect the flame, otherwise it will shut the gas valve, and your furnace will not function correctly. There are three reasons why your thermocouple might be malfunctioning:

It's Broken

A broken or burned out thermocouple won't detect the flame properly, effectively closing the gas valve until you replace it. Replacing a broken thermocouple is cheap and relatively easy if you're mechanically inclined. Contact professional furnace repair technicians at Hot Point for thermocouple repairs if you aren't so confident. It won't cost you much.

It's Dirty

Soot buildup on the thermocouple may block the flame. Under constant exposure to a hot flame, a thermocouple wears down over time. Even a slight residue can make the thermocouple malfunction. The fix here is as easy as removing the thermocouple, cleaning it with a wire brush or something coarse (even an ordinary dollar bill works), and replacing.

If removing and cleaning the thermocouple is something you're comfortable doing, perform this routine maintenance annually. This is DIY furnace maintenance you can perform on your own to extend the life of your furnace and avoid emergency repairs.

It's Not Lined Up

The pilot light flame needs to completely envelop the top of the thermocouple rod so it knows the flame is on. If the thermocouple isn't lined up correctly, it won't read the flame, and will shut the valve for the gas.

I'm not touching it. Help me!

If you attempt to repair or replace the thermocouple on your own, remember to close the gas valve and shut off power to the furnace by flipping the breaker first to avoid an accident.

2) Pilot Orifice is Dirty

If you can manage to get the pilot light lit for just a moment, inspect the flame. The pilot light is supposed to be a strong blue cone, not a weak yellow flame. A weaker flame won’t envelop the thermocouple properly. The pilot orifice may be full of dirt. Cleaning out the pilot orifice means disassembling the pilot and clearing out the debris using a needle or compressed air. If you’re not eager to start tampering with crucial parts of your furnace system, furnace repair experts at Hot Point are just one phone call away to help you out.

3) Bad Gas Regulator

A bad regulator in your natural gas meter outside your home will affect all of the gas appliances in your home, including your furnace, dryer, stove, etc. Your furnace may not be getting enough gas to keep the pilot lit. If you notice pilot problems in several of your household appliances, this may be the culprit. Contact your utility company immediately.

4) Fluctuating Natural Gas Availability Based on Demand

There could be nothing wrong on your end. When natural gas consumption peaks, the “gas grid” in your area may be nearing its capacity and lower the gas pressure intermittently. Even the slightest hiccup in gas supply to your furnace could be enough for the pilot to go out. Ask around your neighborhood and find out if anyone else has had issues with their natural gas. Get in touch with your utility company if the problems persist.

5) Improper Air Flow, or a Strong Draft, Blows the Pilot Out

If your pilot light re-lights easily after going out overnight, it’s possible it was blown out by a draft. This can happen on excessively windy days or nights. A leak in the output duct of the furnace could cause air to blow into the area. Keep every intake air register in your home open and clear to avoid a “vacuum” effect in the inlet.

Waukesha Furnace Repair Pros Help You Diagnose and Repair Pilot Light Problems

Do-it-yourself maintenance and repairs can only go so far, unfortunately. If your furnace is still malfunctioning after you’ve repaired or replaced the thermocouple and determined the flow of gas isn’t a problem, you’ll need the aid of an experienced professional to figure out what’s wrong with your furnace.


Hot Point Heating and Air Conditioning offers flat rate pricing on all of our Wisconsin repairs, meaning we charge exactly what we quote and don’t stray from it. Many HVAC techs will try to employ shady, scammy tactics to get the most money out of you. Hot Point furnace repair experts guarantee integral and trustworthy repair services. Every time.

Contact furnace repair professionals at Hot Point today to permanently fix problems with your pilot light.