Something like Anti-seize copper-based paste is the answer to threads subject to high temperature (exhaust-related most likely).

 

The sensors came with a good bit on them. I figured adding any more to the mix really wouldn't help all that much. It just seems that you have so much heat running through the area that going too tight would cause problems with or without the anti-seize.

 

So I believe the smoke is leaking oil. Pulled the PVC breather hose to find and obscene amount gunk in every hose. Pressure builds and you get leaks apparently. How can I clean my valve covers? Gasoline soak? The plastic housing connected to the intake manifold was gunky too. Is it easy to pop the intake cover off and lean the manifold? I assume it needs it. Any other things I should be thinking about because of the gunky PVC?

 

Hello I have a 2003 Audi A6 I get error codes P0421 and P0431. I guess my O2 sensors have gone bad. I went to the mechanic and he has asked for $1000 which is a little too much for me. Would anybody here be able to help replacing the O2 sensor either with a video or a step by step documentation I will really appreciate it.
Thanks

 

Oh man - I just replaced mine 2 weeks ago but I didn't take any pictures, sorry. I have the 4.2 and the passenger side was a b*tch.

For the passenger side you need to remove the MAF/intake hose to at least have some sort of access to it. At this point you might want to disconnect the sensor already from the ECU. Get a very long extension (at least 12" or longer!) and a regular O2 socket with a swivel head. First take the socket and guide it onto the O2 by hand. This might take a while and be patient (took me 60 minutes because I dropped the socket like 10 times). Once the socket is on, get the extension and swivel head into it and start using the ratchet (use pb blaster if it is stuck). Once it is out, screw the new one in by hand, attach the socket, use the ratchet again (or preferably torque wrench). This literally took me almost 2h hours due to the roomy restrictions in that area. I'm sure now that I have done it it will be under 1h.

The drivers side takes like 10 minutes:
I used a crowfoot O2 socket for this side for easier access. First remove the coolant reservoir, disconnect the O2 connector going to the ECU and just like above guide the socket onto the sensor with your hand first, then attach the ratchet and remove it.

With both sides I used the extension and roughly the same angle from the center back end of the engine. This was the best access for both in my case.

FYI earlier in this thread there was a much more detailed list of how to attack this: https://www.audiforums.com/forum/aud...2/#post1319256

Check it out if you need additional help or simply ask more questions
Good luck

 

Thank you so much for the instructions. Would you know which oxygen sensors would fit in the 2003 Audi A6 3.0 on the drivers side and passenger side. I did research and looks like driver side has Bosch 16132 Oxygen Sensor, but I am not quite sure of the passenger side.

 

The easiest way to make sure you buy the right ones is to check the part numbers @ Bosch Vehicle Part Finder

There are 3 listed for your car:
17353 Oxygen Sensor - Upstream 2 per car
16978 Oxygen Sensor - Downstream Right 1 per car
16132 Oxygen Sensor - Downstream Left 1 per car

If you want to replace the pre-cat ones (before the cat, which was the instructions I posted) then you need 17353. Those are identical, so all you need to do is buy 2 of them.

16978 and 16132 are for post-cat (after the cat).

The Bosch Oxygen sensors with the numbers I posted are direct fit and no modifications are needed. If you decide to go with the universal ones (different part numbers and a little bit cheaper) then you will have to make your own connector and figure out the wires. I wouldn't go cheap here and just spent the extra dollars to get the "plug and play" version unless you love wiring

 

yep, thanks I think I ll go with Bosch parts since I am not into wiring and stuff. Also by any chance would you know for the error code P0421 and P0431 which oxygen sensors would I need to replace?

 

I mean pre cat or post cat? I am sorry for asking so many questions but this is fairly new to me.. I really appreciate all your help. Thank you!!!

 

Now with these codes it doesn't really specify which ones but since they are related to the cats only I'd suggest the post cats. Another thing you probably don't want to hear is that if your still have the same error after replacing the O2s then it is possible the actual cats are bad (and they are expensive $$$$). Also the O2s should be replaced once you reach the 100k mark (or when you get the CEL).
So if you have more then 100k and those things and have never been replaced, do all 4 at the same time since it is always better to have them within the same age range.

Unfortunately I cannot guarantee that replacing just the O2 will make you CEL go away since as stated above there could be more then 1 reason you have the CEL. I read that this can also happen if your engine is running rich. Anyhow for now if you want to go the easy route, check for vacuum leaks and replace all 4 o2s.