I can not find the O2 sensors on my 2006 Porsche Cayenne Turbo. where are they and how much work is it to replace them?

 

They are on the primary-cat pipe (on top) thats located just after the turbochargers. Replacing them?? Good question, shouldn't be too bad with the right tools. Once you get the 2nc cat pipes off...you have more room to work. Taking off the front wheels and inside fender covers should give you more access as well.

 

O2 sensors: Thanks much. I will look into this.
Jerry