how do you change an oxygen sensor

[row503]

hi im kinda of new to the forum and i found so much useful info but i have been looking and have not found any thing on how to change an o2 sensor i have a 99 clk 320 i would appriciate any help i could get and thanks in advance i would like to do it myself instead of paying some body a grip of cash when it could be something i can do my self

[bbearden26]

Its pretty simple really. You can buy the wrench from most auto part stores. Get the O2 sensors from online as that is the cheapest source. There are four sensors that need to be replaced: 2 left and right bank pre-cat and 2 left and right bank post-cat. The pre-cat sensors are easy to access, the post will likely require you to lift the car and crawl underneath to access. You disconnect the wires from the harness first. Spray the sensor area with penetrating lubricant to make it easier to remove and then remove the sensor. The installation is the opposite of removal and you might consider adding some dielectric grease to the connection point in the harness. Best of luck--this is a fairly simple DIY--some tight spaces but you should be able to manage.