Any mechanic worth their salt knows how to “read” a spark plug to find clues to diagnose engine trouble, but did you know you can do the same thing for an oxygen sensor?

If you’re not familiar with what we’re talking about here, read this: A Guide to Reading Spark Plugs

Yup, inspecting your oxygen sensors can tell you an awful lot about the health of your engine, and the experts over at NTK Oxygen Sensors will show you how to do it. As the sister company to NGK Spark Plugs, the folks at NTK have a ton of experience with the engine combustion process, specifically the aftermath. And they’re eager to share that knowledge with you too.

This in-depth video will show you what to look for when inspecting your oxygen sensors—it’s definitely a good watch if you’re looking for clues to solve a nagging engine issue.