So I recently came across a post on another forum regarding counterfeit spark plugs coming from both Amazon and Ebay. Supposedly, it was only NGK that you had to worry about, but turns out the DENSO has become subject to these as well. I thought I bought my last set of spark plugs from the dealership, but turns out I got them from Ebay. Well, shit. So down the rabbit hole I went. Instead of writing everything that has already been written, here is a post from someone who does about as good a job as anyone at showing examples of fakes: How to spot counterfeit Denso Spark Plugs My key takeaways being that there shouldn't be any bulging around metal engravings engravings should be deep the writing on the ceramic should be centered between the base and the first rib "DENSO" should look like a slightly different marking than the model number below it the plug end should be matte and not have any gloss to it sleeve protector should be longer than the plug (i.e. protects the ground rod in addition to threads) images printed on packaging should be crisp The fact that I even have to question this is annoying. I didn't know that counterfeit plugs were a thing.