I’ve used these before and they have worked. I Just purchased a new car with p0421 code so I thought I give it a try again.. it did work, However this gave me a totally different code for system to lean.. “getting to much oxygen” so I took it off. Would rather just have the p0421-cat code over the lean code. So I removed the spacer. It’s definitely worth a shot tho it’s a cheap and easy enough to install. It did work on my old scion tho just not my newer 2.0 Lancer.