Thexton THE404 Spark Tester

It does exactly what it's supposed to and does it well. Definitely a quality tool.

I used these style spark plug testers at school. they are EXCELLENT! You can adjust how big you want your spark to be, which easily helps you determine if your coil packs or distributors are getting enough voltage or if your spark plug is bad.Long story short on how to use this tool: You unplug your coil/spark plug wire (depending on the type of ignition system of course) and connect it to the end of the tester that looks like the top of a spark plug. The piece that has an alligator clip just clips onto any part of the car that is metal in order to create a ground. Once it's hooked up, start your car. If you're able to get an arc going across the points in the tester, especially when it's adjusted all the way out, then you know your coils/distributor is getting plenty of voltage so it is good, and is most likely your spark plugs. If you barely get any spark, especially when the tips are almost touching then you're not getting enough voltage for some reason, which indicates a bad distributor/coil packs, or bad wiring somewhere between the coil packs/spark plug wires and the positive battery terminal.This tool is an excellent little diagnostic tool to have, and I recommend that every mechanic should own one! This is a great tool to help fix misfires and other ignition issues!

I got this to spark test my Honda 4 stroke 30hp outboard. The plug boots on the engine are too small to fit this. So I can’t speak to any other features, just be aware that it may not fit your application. Electrode tip is 6mm/0.23” in diameter so measure your boot first before buying.

Great little tester. pretty well made .

Works great saves time don’t thank about just buy it

A must have for troubleshooting vehicles with high energy ignition systems.It provides a very simple way to test your spark plug coil packs.This spark tester is easy to use.I like the ability to adjust the spark gap to match the system that I am working on.The spark is easy to see when the ignition system is working properly.

Number 1 reason to buy this over the glowing type tester is you can accurately measure the strength of the spark. I had a weak ignition coil but it was firing. This tool tells me my spark can only arc half the gap of a normal output. Saving me lots of time and money, since I can focus on improving the spark quality. Before using this tool, I thought I had bad gas, dirty carb, worn rings even sheared timing gear. Solved my chipper no start problem. It wasn't clear in the instruction that you do not test it in-line with a spark plug - it tests by acting like an adjustable spark plug outside of the combustion cylinder.

This thing works great helped me diagnose a weak coil! 10/10 would recommend!