After a muffler pipe repair, was getting a check engine light on my dashboard. Traced it down to a couple codes, one of which was downstream O2 sensor. Of all the fixes I do on vehicles, this was one of the easiest. good light, a set of oxygen sensor sockets (they have a slot to go around the wire, you can buy right here on amazon) and a socket wrench with extension are recommended. Replacement took 5 minutes (you may need to use some penetrant spray if the threads are really rusted - my car is a 2012 and I did not need spray). Note: these sensors can become corrupted if you have work (like I did) near the sensor - like welding, etc. A good shop should remove these before they do work nearby. Don't waste your time on cheap replacements - get the manufacturer recommended one - they are not that much more money, they will last the life of your vehicle and you don't want to do a job twice (I barely have enough bandwidth to do a job once). Good luck !