I pulled one of the plugs I bought on Amazon and installed several years ago. Bought directly from Amazon, not third party.
First of all, only 35k miles and this plug did not come out smoothly, I think I will use anti-seize on the next change despite the warnings.
This replacement plug was not bought as a Toyota part but as a Denso part.
Says “Japan” in the engraving.
Mine passes most of the counterfeit checks.
Good screen printing.
Good looking center and ground electrodes: width, weld, color.
Good gasket feel and gap.
Passes the scratch test for plating or paint.
But fwiw, the engraved printing is not really centered, it’s a bit low.
I think it’s genuine and my performance and mileage is normal.
Here’s a link to the Denso Counterfeit Guide..l
https://www.denso-am.eu/media/137417...paper-_pk3.pdf