5 Reasons the Pilot Light Won't Stay on in Your Gas Fireplace

a lit modern gas fireplace in glass
  • 1-2 hours
  • Intermediate
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When the flame fails on your gas fireplace, the problem often lies within a tiny component with an important job.

Use this guide to figure out the top reasons your pilot light won’t stay lit on your gas fireplace.

To understand the process of troubleshooting a gas fireplace pilot light that won’t stay lit, you must understand how the system works.

There are really only a few components involved, but each is essential for success. Basically, gas is carried into the unit through gas lines.

The pilot light button allows gas to flow to the pilot light. Then the ignition switch provides the electrical spark to ignite the gas.

Once the pilot light is lit, the thermocouple senses the flame and allows the gas valve to open, releasing gas so the fire can start.

If any component in the chain fails, you won’t have fire. The primary point of origin is the pilot light, so if it won’t remain lit, that's where the repairs begin.

1. Corrosion

Oftentimes you don’t actually have to repair or replace any parts in a gas fireplace when the pilot light won’t stay on. Often the problem is simply that you need to do a bit of cleaning.

If the pilot light throws a spark when you push the ignition switch, or starts but then fizzles out, the problem could be buildup on the ignition parts.

To remedy this, use a green scrubbie or piece of fine-grit sandpaper to clean any white residue or other debris off of the pilot light, thermocouple, and thermopile.

These components are all in close proximity to each other, and it won’t take long to do. Once the debris is gone, try the pilot light lighting process again.

2. Thermocouple Needs to Be Replaced

Without a doubt, the most common reason the pilot light won’t stay lit is due to a dirty or faulty thermocouple.

Since you’ve already cleaned the parts, if the pilot light still won’t remain lit, it’s likely the thermocouple needs to be replaced.

It’s not an expensive or difficult process. With a basic understanding of electrical components and gas safety, you can swap it out in short order.

However, if you’re not comfortable with electrical and gas systems, it’s a relatively inexpensive repair for a professional too.

man repairing gas fireplace

3. Gas Supply Issue

Gas pressure and quality changes over time and can get out of whack. It’s kind of like running a car built for premium fuel with regular gasoline.

It might not happen right away, but eventually, the lower-quality gas is going to affect the system.

A gas supply issue is something you’ll need the gas company to address. They will send a trained professional to test the gas supply and make the needed adjustments.

4. Pilot Light Button

The pilot light is the metal component where the flame comes out. If you’ve cleaned it and it still isn’t working, it may need to be replaced.

However, for this topic, we’re discussing a pilot light that lights but doesn’t stay lit. In that case, it’s possible the pilot light button could be faulty.

It’s unlikely, but if the button doesn’t provide the right level of pressure, it will fail to open the gas line to the pilot light. Once turned to the ‘On’ position after lighting the pilot light, it may not function properly, creating a gas flow issue.

Similarly, most pilot lights have a reset button, so always start by resetting the system before doing a deep dive into other individual components.

gas fireplace

5. Faulty Gas Valve

Finally, you could have a faulty gas valve. If everything else seems to be functioning properly, it likely is the culprit, although this is much less common than the thermocouple.

Regardless, nearly all professionals advise against ever trying to replace a faulty gas valve yourself. Call the pros in for this one.

In summary, if your pilot light is struggling to stay lit, try a reset. Then clean parts and replace them if that doesn’t help. If all else fails, call in the professionals.