Ok so I am trying to change both o2 sensore that are pre-cat on my 01 s4 avant. Are you supposed to be able to change them from the top of the blockor through the wheel well? I even bought the wrench to get to them.... HELP!!!!!! Ican't get to them from the top....

 

yeah, you have to remove the airbox *all of it* the silver loking y pipe and move the coolant tank out of the way make sure you unplug it from the bottom. Also make sure you undo the batt so you dont fry your self and undo the o2 plugs from the top. Once you do all that you can see the right side o2 put you crows foot 22mm on the o2 and put your mile of rods and turn it well try too or hit it will a rubber mallet. Now the left *drivers side* one is way harder to see but look and you can see it jsut get the crows foot in there and start trying to turn it , it is hard very hard to turn so i used some pb blaster and then it broke after 5 mins of me cussing and trying to brake my wrist. Hope this helps at all man
paul

 

Cool thanks man.

 

i purchased an 02 sensor tool on ebay. It was 15 dollors. I removed both o2's without removing anything. However it would have been easier with the y pipe disconnected.
The tool is a Life saver though....you should buy one.
heres the one i bought. http://cgi.ebay.com/ebaymotors/ws/eB...m=250244746243
there are other types for sale but this one works best with the heat shield and the tight area.
good luck and use graphite grease on the threads when putting the new ones back on.

 

yeah that is the part I used also but got mine from advanced auto parts.

 

I am going to attempt this again tomorrow. Started taking everything apart yesterday but thought that there had to be a better way. Now that I know there isn't... Back in we go. I did purchase the ECS O2 sensor removal tool but I wish the handle was longer. Something tells me six beers into it and nothing will be a problem...

One question though. Do you have to remove the allen bolts and heat deflectors????

Thanks for all the help and input though guys.

 

no you dont have to, there sound be enough room to take it out with out doing that.

 

Well I removed everything mentioned above and after 3/4 of a can of liquid wrench they wouldn't break loose. Any more ideas??? I even tried to add another pipe with the ECS wrench for added leverage and nothing...

 

did you use the pb blaster or liquid wrench, if the pb wrench let it sit for some hours then get back to it. Also make sure you are turning it the right way , haha cause I was not the first time for some reason I was thinking right was lose hahaha. My driverside was really tuff i mean took two days for me to get it off. Keep trying man you will it.