This spark plug tester functions exactly as described, is easy to use, and a valuable item to have. I’m pleased with the size and quality, and it has been reliable thus far.

I have a friend that changes sparkplugs for everything. I tell him he is wasting his money and he doesn't believe me. So with this I show how the ones he just took out looked exactly the same as the new ones going in. Then I showed him what a bad one looked like. This item worked as expected to show which spark plug is actually bad if at all.

With modern electronic ignition engines, being able to accurately test spark plugs help reduce unnecessary spark plug replacement, so I thought I would give this a try. Excellent choice. This plug tester is well made out of good quality materials. Fit and finish are good. Very easy to use. I particularly like that you can simulate different RPMs giving a good indication of how the plug will perform in actual use. Highly recommend. 5 stars.

Because I like to make sure things are running correctly on things I own, I decided to order this spark plug tester. Actually, I ordered it because I was troubleshooting an issue on my boat and because it's an inboard/outboard(I believe that's what it's called), where it has the motor, the size of a trucks motor, inside the boat, it leaves very little room for testing for spark issues with other types of spark plug testers and because of my bad back, I can't test them that way. So I took each plug out one at a time and tested them, using a brand new spark plug of the exact same kind. It was really easy and obvious to see when one of them wasn't sparking like it should be and so I found the issue. Since then, I tested the sparkplugs in my wife's jeep and thankfully they were still in good condition .

I used it, it work great. not too much to say about it other than it does what it is supposed to do. I am very pleased with it.

Honestly it would probably be better if my husband wrote this review since he's really the one that uses it. But he tells me that it works great for quickly checking spark plugs. I'm not sure the quality is top of the line, but it's great for the price point. It's not something a professional would want to use in their shop, but it's a great little tool to have on hand at home. Simple and easy to use.

It’s easy to use and provides quick results, but the build quality feels a bit flimsy, which raises concerns about long-term durability It works well for occasional use but might not meet the needs of a professional mechanic. A solid option for DIYers, but it could benefit from better construction and clearer calibration

I bought this Spark Plug Tester because my car was misfiring, and I wanted to test my spark plugs. Honestly, I felt like a mad scientist in my garage, and it's been pretty interesting to use at home. This device has dual holes that let you test and compare two spark plugs side-by-side, which is great for seeing the ignition intensity and performance differences in real time. It works by simulating engine RPM, adjustable from 0 to 6,000 RPM, using a rotary switch (basically a potentiometer) for easy control. The higher the frequency, the stronger the spark, making it easy to evaluate plug performance under various conditions.Setting it up was easy: it comes with a 12V adapter and it’s pretty straightforward to set up without any unnecessary complications. The device also includes a power indicator and two high-voltage indicators for each plug, making it easy to monitor the test. The device has two slots, so I placed a used plug on the right side and a brand new one on the left. When I cranked it up to about 3,600 RPM, I could immediately see the difference, the used plug’s spark looked like it was having a bad day, while the new one was sparking like it just got promoted. It really helps you visualize just how much a worn-out plug can affect performance!!One of the things I appreciate about this tester is how intuitive it is. The controls are simple, and there’s an immediate visual difference between a good plug and one that’s past its prime. This tool is perfect if you want to understand what's going on with your spark plugs without feeling like you're solving a Rubik's Cube blindfolded! LOL! Even if you’re not a pro mechanic, just seeing the difference in spark quality makes it easy to understand whether a plug is still good or if it needs replacing.Just know though, that this tester is designed specifically for 12mm spark plugs, and it has a socket diameter of 13mm. If you're using smaller plugs or long spark plugs, the provided washers can help stabilize the setup during testing. That’s something to keep in mind if you’re working with a variety of different engines. Still, it works well for most plugs I've tried. I use, especially common 12V gas engine plugs. Watching the sparks in action makes it really easy to spot any performance issues that a plug might have, like inconsistent firing or weak sparks, which can lead to all sorts of engine problems if left unchecked. The only thing is that it really needs to have a cover to place over the spark plugs while testing, for safety. Also, some sort of storage case is very much needed!!All-in-all, this tester has been a cool addition to my home DIY setup, making me feel way more confident in diagnosing spark plug issues in the future; and maybe even a little like a spark plug whisperer in the neighborhood!! LOL! Before, I was often left guessing about the condition of a plug, especially when it wasn’t visibly damaged. Now, I can actually see how the plug is performing under simulated conditions, which takes a lot of the guesswork out of it. It may not be something I use every day or very often since spark plugs typically last for awhile, but when I need it, it makes the job a whole lot easier!