Replacing an O2 Sensor?

[Nola111]

Hi all,

I'm looking to try and replace my O2 Sensor myself on my 2006 Passat 2.0T and I'm wondering if someone could point me in the right direction for a DIY walkthrough? Searching on here brought me a nice walkthorugh with pics, but it was for a 99 Jetta, definitely not similar enough to my 2006 Passat 2.0T. Google wasn't much help either. Lots of forum hits but none that applied to my car.

Here are the trouble codes to show the exact sensor that is troubled:

000313 - Oxygen (Lambda) Sensor B1 S2: Response too Slow
004372 - Oxygen (Lambda) Sensor; B1 S2: Internal Resistance too High

Any help would be greatly appreciated!

Thanks,
Patrick

[najel]

I think that the S2 sensor is the one behind the cat. Should be easy enough to replace, find where it is plugged in (you probably have to remove a cover to get to that) unplug, then unscrew preferably using O2 sensor wrench. If you have a spark plug thread chase, use that to clear the threads, will make it easier to install the new sensor. Now screw new sensor in carefully after applying antiseize if it doesn't have any (if OEM it should) plug in, replace cover, clear codes, run guided readiness or just drive and keep an eye on CEL.

[Nola111]

I think that the S2 sensor is the one behind the cat. Should be easy enough to replace, find where it is plugged in (you probably have to remove a cover to get to that) unplug, then unscrew preferably using O2 sensor wrench. If you have a spark plug thread chase, use that to clear the threads, will make it easier to install the new sensor. Now screw new sensor in carefully after applying antiseize if it doesn't have any (if OEM it should) plug in, replace cover, clear codes, run guided readiness or just drive and keep an eye on CEL.

Najel, thanks so much for your post, that is very helpful. I have just a couple of follow-up questions: Is the sensor behind the cat under the car or under the hood? And also, what is "guided readiness?" Is that a function of the VCDS software?

Finally, does anyone have a VW part # for this particular sensor? It does not appear to be listed in the trouble code log.

Thanks again!

[najel]

No problem. One thing I forgot is that you should spray the sensor down with penetrating fluid such as WD40 before you start and I would let it soak for at least 30 minutes, the longer the better. This will make it a lot easier to remove it.

Guided readiness is a function in VCDS, simply go to 01 - Engine, then clock Readiness, there is a button in there to set readiness. It will tell you step by step what to do. This is not required though, only if you want to see right away if your code goes away. If you don't do this step, the car will do it by itself over time. If the code comes back you will get a CEL again then.

And the S2 sensor is the one behind the cat, so it would be under the car, not the one under the hood. To get the part, you can just check the typical websites like ECS or DBC or German Auto Parts. They should all carry the sensor, and I would guess that most of them would carry the OEM and/or Bosch. Look for Rear Oxygen Sensor or post-cat or something like that.

By the way this diy here is for a GTI but it should be very very similar to the Passat since it is the same engine. Either way, the general procedure is the same. http://www.golfmkv.net/blog/archives/71#

[Nola111]

Well I've succeeded in replacing the after-cat sensor on my own thanks to the great help from Najel, but unfortunately, after a couple days of driving, the CEL came back on with the same two fault codes (plus three others which I'll post about in a separate thread).

I used the Bosch O2 sensor and everything went very smoothly with the install, so what could it be? Is it possible that there's something wrong somewhere from the connector on to wherever the wire ultimately leads to?

Any further help would be greatly appreciated!!!