DocWyte

Something I can easily do in my garage with hand tools, or something I need to have the car up on a lift to do?

TIA!

Mike@VAST

but it's not so bad w/some proper tools...get a slotted o2 socket (7/8" or 22mm) and a long extension(18" or so). be sure to cut any ties off of the wiring to the sensor so you can spin it a bit w/o damage. spray some penetrating oil on it as you are taking it out, once you crack it loose, you can undo it by hand...removing the y-pipe makes it easier, as well as moving the coolant reservoir out of the way.

tighten the new sensor w/a stubby 22mm, if you can get it in there (if you have heat shields, forget it)...otherwise snug it down w/your original tools and put a little anti-seize on the threads.

AudiS4guy - NorCal

when he says long extension...he really means long. I had to use 2 foot ext.

Imolsify

02 sensor was TIGHT!

Steven Lin

The sensor can only be accessed from above. There's no need to remove the Y pipe. Just remove the 3 screws for the coolant reservoir, unclip the coolant sensor on the bottom of the reservoir and put the reservoir towards the driver's side. The sensor should now be clearly visible. Remove all engine covers! I cracked two of mine with sharp elbows. Doh!

Even though the sensor is 22mm, the standard 7/8" slotted O2 sensor socket works fine, although you'll need at least one universal joint. A long extension is necessary, too, as others have said. Some writeups say that two people are needed, but I was able to do it solo. Lean over from the front and work the socket onto the sensor, starting from the passenger side and going under the Y pipe and through a couple of hoses. The sensor is screwed on pretty tight. You'll need a breaker bar to apply enough torque to crack it loose.

BTW, the other end of the sensor is mounted on the firewall. It's the first connector on the left, of the group of connectors just to the right of the centerline of the car, near the coolant reservoir. It took me a while to figure out how to detach the connector from the firewall. Hint: it twists off.

If your hands are small enough, I suggest you screw in the new sensor by hand. That way, you won't have worry about twisting the sensor wire too much to do the final tightening with the socket.

DocWyte

There is a large conical heat shield blocking everything. There are two allen head bolts holding it in, but they practically look welded in place...

Any suggestions?

Imolsify

<img src="http://www.engr.uconn.edu/~bid03001/engine.jpg">