In many instances, high performance and high maintenance are synonymous, but SureFire has invested more than 40 years of R&D to produce premium tactical illumination tools that combine life-saving high performance and lifelong durability with minimal upkeep required.

SureFire FlashLight Maintenance
SureFire Lights provide virtual fail-safe operation. Tending to a few basic maintenance items will help keep your SureFire ready for use when you need it most.

In fact, SureFire handheld flashlights are so highly refined that the flowchart is relatively short if you should ever need to diagnose a potential problem. Here’s a basic SureFire flashlight maintenance guide that addresses the most common issues with SureFire lights powered by 123A or 18650 batteries and a few tips on how to maintain your light for top performance. Follow along as we perform them on a SureFire EDCL2-T.

REPLACING BATTERIESSureFire Flashlight with SureFire SF123A batteries

The weakest link in any SureFire handheld flashlight is usually the battery. Some 95 percent of all functional issues are due to depleted or improperly installed batteries. In addition to preventing activation, depleted batteries can sometimes trick the owner into thinking there is a more serious problem by causing the light to flicker. On multi-output lights, depleted batteries may only allow the low-output setting to function properly.

That said, it is important to start any troubleshooting by replacing the batteries in your light with brand new batteries, even if you are confident the batteries are good. Ensuring that you are dealing with fresh batteries rules out the possibility that your light may have been inadvertently left in the “on” position or that your batteries have seen more runtime than you might recall. Simply swapping-in new batteries is a more effective way to ensure adequate power than attempting to determine if a battery is good by using a voltmeter. The latter may not be accurate as several SureFire lights have very high power requirements.

If the light functions properly with fresh batteries, you’re good to go, but here’s an important caveat: Never use inferior 123A batteries that are not made in the U.S.A. Most 123A batteries sourced from overseas are inferior in quality and can cause thermal venting resulting in fires, damaged property and potential harm to the user. The safest way to ensure that your light is operating on the best-quality 123A batteries is to use SureFire SF123A batteries, which are optimized for use with SureFire lights.


At the same time that you are replacing your batteries, there’s also a quick and easy test that can rule out the tailcap as an issue:

  1. With the new batteries still in the light, unscrew and remove the tailcap.
  2. Using a metal object such as a paper clip or key, simultaneously touch the flat center of the exposed negative battery terminal and also the rear metal rim of the flashlight to complete the circuit. This test should allow you to activate the light.
  3. If the light turns on, then you have relegated the issue to the tailcap.

TAILCAP/HEAD CLEANINGSureFire flashlight tailcap being cleaned

Just like the rest of your kit, SureFire flashlight maintenance should always include proper cleaning. Most of the time a tailcap problem can be traced to dirty or greasy tailcap threads, which may keep the electrical circuit from being completed and prevent activation. To eliminate this possibility:

  1. Clean the threads of the tailcap, using a cloth, paper towel or similar absorbent material.
  2. Clean the flat surface at the end of threaded section and corresponding area inside the tailcap to ensure positive electrical contact between tailcap, head and body.
  3. For SureFire lights with removable heads, this cleaning process should be repeated to ensure that the head threads are also free of debris.

If the cleaned tailcap still does not activate the light, contact the SureFire Tech Support team and we can send you a replacement.

The O-rings of your SureFire light may become contaminated with heavy use, which can decrease the body’s ability to repel moisture and other debris from making its way inside the body. Removing dirt or debris from O-rings can be accomplished by using a cotton swab or similar material to lightly clean them. Once clean, simply coat the O-rings with silicone grease, such as Nyogel or SCUBA equipment grease. Grease only the O-rings, not the threads. Do not use spray lubricants or petroleum-based lubricants. And do not use acidic, alkaline, or petroleum solvents to clean any part of your light.


Over time, or when subjected to high round counts, SureFire flashlight and WeaponLight lenses may be subject to carbon buildup that can hamper the clarity of the light. Preventive maintenance before you shoot is the best way to combat this buildup. Simply applying some Chapstick or non-petroleum-based lubricant to the clean lens before shooting should enable you to easily wipe the carbon off at the end of your training day with a cloth; the carbon will adhere to the layer of Chapstick or lubricant and not directly to the lens. Be advised that most firearms lubricant is petroleum based and will degrade the O-rings inside the bezel over time.

In the event that carbon buildup has already clouded the lens, simply scrub the window with a pencil eraser or a with a small amount of toothpaste applied to a soft cloth. Finish this cleaning with an alcohol swap and your window will be cleared and ready for action. At the start of your next range day, reapply lubricant to keep the window clean.

If you still have issues after performing all of these SureFire flashlight maintenance tips, including fresh batteries, performing the “paper clip test” and cleaning the threads on the tailcap and head, or if you have other maintenance-related questions, please call SureFire at 1-800-828-8809 and ask for Tech Support. Our friendly, knowledgeable staff is happy to answer questions and provide solutions for any need. When you choose SureFire illumination tools, suppressors or other premium gear, you don’t just buy a great product. You join a family. Rest assured your SureFire family stands behind you for life.

For more information on SureFire’s line of combat-proven handheld flashlights, hands-free lights and WeaponLights, visit