Thermacell Won’t Stay Lit? Try These 4 Easy Fixes

When out in nature — whether camping, hunting, or hiking — a Thermacell is an excellent piece of gear to keep you protected from mosquitoes and other biting insects.

While these devices are tried and tested, sometimes they run into some problems. One of the most common problems is that the Thermacell won’t stay lit.

A Thermacell product that won’t stay lit is likely due to an empty fuel canister, a dirty machine, or the product is in need of replacement parts. And in some cases, it could be that there’s not enough air density to light the butane — this is common at higher elevations.

So, the next time you’re Thermacell won’t stay lit, Try these 4 easy fixes:

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Thermacell Won’t Stay Lit? Try These 4 Easy Fixes

Thermacell Won’t Stay Lit?

When a Thermacell product struggles to stay lit, it’s usually due to one or more of the following issues:

  • Lack of fuel
  • Dirty parts
  • Broken parts
  • Stuck pieces

In some circumstances, such as high elevations, the butane lacks enough air density to light or remain lit.

How To Fix a Thermacell That Won’t Stay Lit

1. Refuel the Canister

It might have been a while since you last refueled your Thermacell unit. In that case, turn off the product before refilling. 

There may also be damage to the canister that made it leak. Like with refilling, turn off the unit before you change out the fuel cartridge for a replacement. 

2. Disassemble and Clean the Parts

While Thermacell products should never be watered down or soaked in cleaning fluids, cleaning the parts could solve your issues with getting your unit to light or stay lit.

For basic cleaning, the company recommends wiping with a damp rag. 

If you accidentally get water in your unit: 

  • Take the product apart with a screwdriver.
  • Let the unit air out for several hours.
  • Screw the pieces back together, taking care not to screw them too tight.

Most people voice in reviews that if they could not get the unit to start working after quick solutions would opt to take up Thermacell’s offer to repair or replace the product — but some customers take managing their units to another level. 

Sometimes dust and other particles can get into the smaller parts of the unit. For dust, some customers have taken out the smaller pieces and blown the dust away.

Thermacell Won’t Stay Lit

The main caution with this approach is that it can be hard to keep track of the parts and put them back. Others have used pipe cleaners or gun cleaning solvent for wiping and compressed air for drying.

For a more meticulous approach, consider using a toothpick or cotton swab to loosen grime in tight areas and then wipe it down with rubbing alcohol. Ensure that it dries completely before using it again, as rubbing alcohol is flammable.

3. Repair Broken Parts

Thermacell products can be sensitive to tipping over, causing them to break. Even the tiniest crack in the parts that deliver the butane fuel can prevent the unit from lighting. 

The easiest way to tell if this is your issue is to listen for the hissing of escaping gas or the smell. 

The following YouTube video shows how to fix a butane leak, using a damaged Thermacell Backpacker as an example:

In the video, he takes these steps: 

  1. Take apart the product. 
  2. Find the piece that has the crack. 
  3. File the area so that it is rough enough for the sealant to grip. 
  4. With a toothpick, mix the epoxy. 
  5. Using the toothpick, apply the epoxy to the cracks and the area around them. 
  6. Allow the epoxy to dry for 24 hours. 
  7. Put the unit back together. 
  8. Turn the Thermacell on. 

Once you’ve sealed the leak, you can test if you have fixed the issue by listening and smelling for escaping gas. Additionally, you’ll want to ensure that the butane lights and stays lit.

4. Check the Small Lighting Parts

If you like the process of fixing your Thermacell product yourself rather than replacing it when refueling, refilling, and cleaning does not work, then you could check the internal mechanisms. 

One part that can cause issues with lighting and staying lit is the spring that responds to the on-off knob. It can get over-compressed and not extend enough as needed to release the butane.

So while you have your unit taken apart, work your way to the spring and massage it apart to help it loosen up. If it responds, put the product back together and test if that was what you needed for reliable lighting.

For more detailed information, check out this YouTube video:

Another possibility, but one you will want to be careful about, is to bend the spark wire into different positions. Some have had luck getting more steady and consistent fuel flow and thus lighting but finding an angle that can give the best spark. 

Thermacell Won’t Turn On At All?

Before diving into the reasons why a Thermacell won’t stay lit, it’s important to ensure that you’re using the product correctly.

First, make sure that the settings are in the correct positions. Next, wait about two minutes before igniting — this lets gas flow out and may fix any ignition issues. Finally, ignite the Thermacell. Thermacell also states that you should wait 10 to 15 minutes after igniting for maximum efficiency.

Some customers on hunting forums and Amazon caution that newer products are more prone to lighting issues. The rotating knob-styled units can be sensitive to being knocked over or dropped a few inches instead of being set down.

Users also report the newer models to be more sensitive at higher elevations when the older units often worked at 10,000 ft (3,048 meters) above sea level.

If for any reason none of the following solutions work, Thermacell encourages its customers to send malfunctioning products for repair or replacement. You can find their return information here

Trust me, I have had to send a few units back over the years, and as frustrating as that process is, Thermacell does stand by their products and will send out or issue a replacement.

Little Things To Try First

Sometimes to get a product to operate, you need to understand its quirks. Try this hunter’s trick:

  1. Turn on the butane. 
  2. Light on the first click. 
  3. Wait for 5 to 10 seconds. 
  4. Ignite a few times.

The Thermacell’s window to the pad will spark and turn red. 

Thermacell Won’t Stay Lit

It also helps to keep the unit on a flat surface while doing this. 

Get Creative for Modern Changes to Thermacells

Thermacell users on outdoor forums have concerns over newer models of around 2012 and later. They have also come up with creative solutions. 

One main issue is that the units do not get as hot as the older models, preventing them from smoking (which released the repellent).

So newer, less-warm models might not be releasing the repellent enough. If you have multiple units, you could keep them near each other, face to face, so they help one another warm-up. 

Problems That Neither You nor Thermacell Can Help

As briefly stated before, Thermacell products struggle in high elevation. The company is transparent about the issue and acknowledges that neither you nor they can do anything about it. The atmosphere at higher elevations is less dense, and that lack of density makes ignition harder. 

If you are having an issue at higher elevations, it matters which product you have. Thermacell claims that many of its products will begin to struggle with lighting and keeping it lit at around 4,500 feet (1,372.6 meters) above sea level and higher.

But the Radius has no limitations, and Thermacell designed the Backpacker to work at up to 7,000 feet (2,133.6 meters) above sea level. 

However, many users have had good luck with other products as high as 10,000 feet (3,048 meters), particularly with older models. 

So, if you have a problem at high elevations, you know why, but do not let the possibility of altitude problems hold you back.

Other Things To Check

Aside from the obvious fuel, and sparking mechanism, it’s important to also check the repellent pads of your unit. Even if the unit is operating correctly, it must have a fresh and repellent to properly work against those nagging ‘skeeters’ (mosquitos).

Replace or Refill the Pad

There are two reasons why you would need to replace your Thermacell d-allethrin or prallethrin repellent pad. 

  • You used it up, and it is time to throw it away and use the next one.
  • You have not used your unit for a long time, such as over winter, and the pad dried up. You would have to throw it up and insert a new one. 

But you can also refill the pads rather than discard them. Some uses have found they could create effective mixes using dry Thermacell pads, permethrin, and water and apply the mixture using eye droppers. 

Both recipes suggest to: 

  1. Mix six parts of distilled water to one of permethrin in a container. 
  2. Use a syringe to migrate to an eyedrop container. 
  3. Use the dropper to apply a few drops to a dry Thermacell pad. 

Permethrin is an affordable common repellent available at farm and home retailers. 

Another recipe suggests adding a few drops of blue food coloring. New Thermacell pads are blue and turn white as they use up. So by adding a few drops of blue food coloring, you can emulate the color-changing process and have a good idea of when you will want to refill the pad again. 


Nothing can ruin a trip in the outdoors quicker than relentless mosquitos. A Thermacell unit is a great alternative to traditional bug sprays or chemicals you put on your skin.

I use a Thermacell during bow season, especially when I’m hunting out of a ground blind when scent control is extremely important.

I hope this article helps you the next time your Thermacell starts acting up. Thanks very much for reading!

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