I searched for emission cleaning but not any usable help. Hope you guys can help. I took my 2012 Chevy Cruze with 79,000 miles in to dealership. It sputters at start up and gives check engine light giving code. Same codes that previously had to replace the cam cover. They already replaced in January and the guy behind the counter said I needed a Emissions Cleaning. He said that is reason it's giving the codes again. That they could do it for $110 (amount in that neighborhood). So looking online not much besides PepBoys and other shops that state they do them. So my question is, what can I do to clean it myself. Thanks for the help, sorry for the long post.