Oxygen sensor on 2004 Audi A6 Quattro

How can I replace the oxygen sensor on an audi a6 2004?

Asked by for the 2004 Audi A6 Quattro
There are several oxygen sensors, but either way, go to
or and get a repair manual. This can save you a lot of time and money, and it will help you with the next repair you decide to do.
1 more answer , 1 more comment
this job is no picnic! a special socket is needed and depending on which sensor, maybe a box of band-aids. unless you can replace easy stuff like brakes,oil,etc i'd keep paying for replacement of sensor as the prefered option. no offense intended.
A slotted socket is about $15-20. There are 2 x 2 (paired) sensors - (4). You will need to have good access under the car to get the torque needed to remove a couple of them (Plus an extension).