You should ask in the B6 subforum. This one is for B5.
Volkswagen Passat B6 Discussion | Volkswagen Passat Forum (passatworld.com)

 

That's my fault. It was in a regional forum and I accidently selected B5 vs B6 to move it to.

 

Bank 2, sensor 1... is theoretically I think the only one that you can get to without removing the intake manifold... it still isn't the easiest, but it can be done.


IMO... I would replace all 4... but... it's a pain in the ass. Requires removing the intake manifold, which for the uninitiated is a pain in the ass with the one-piece manifold. Removing the intake manifold (and all of the getting the car in service position) is one of those things where you want to seriously consider anything else that you might want to do while in there... things like valve cover gasket replacement... and all the way to things like pulling and injectors to reseal or replace them. It becomes a slippery slope real quick.

Mike

 

 

Thank you! I figured I should try and replace bank 2 downstream sensor first before taking it to my mechanic. Is that the same sensor you are referring to? The one with the pink arrow is the only one I can reach comfortably

 

Yes... that's bank 2 sensor 2 (downstream). The Upstream sensors are wideband... and the downstream sensors are narrow band and basically just check how well your catalysts are working. The upstream wide bands are what control the fuel mixture and such in the engine. I mean... if you can get to it easily (my comments above are also based on doing this on 4 motion cars, which are much more cramped, and you didn't say that this is a 4 motion car) you really don't have much to lose in changing it out yourself. If it doesn't resolve the issue... then you can decide to continue on down the path or not.

 

Hey Mike, where did you find the diagram that’s posted in this thread?

Also, I have a B6 3.6 4motion and have a code tripping the check engine. It’s the O2 downstream right, Bank 2 Sensor 2, #1K0998262S. The dealership can’t get it out to replace it. How can I confirm that continuing to drive with a bad downstream O2 sensor on this specific model will not have any bad effects on any other parts or cause any issues?

I keep reading conflicting information. Something online said both sensors on a bank work together to adjust the fuel mix and an incorrect mix can do all kinds of different things. Have also seen what you say here, the downstream sensor basically only monitors the emissions after the cat.

If it is only to monitor the cat. Do you have any info on bypassing or deleting both downstream sensors from the system so I can get the engine light off?

Greatly appreciate any info you can provide. VW wanted a ridiculous amount of money if they damage the threads or break it off. Said they will have to replace the cat.

Thanks

 

The downstream sensors are narrow band, so only indicate lean or rich condition. I have one of my cars where I replaced all of the O2 sensors, but still from time to time get the check engine light illuminated due to a catalyst alert. There is no way that I know of to code that out or disable the downstream sensors. I have not replaced the cats because well... they are pretty darn expensive even for a DIY..... there are some cheaper options on ebay, but I cannot vouch for quality, etc. Fortunately for me, I'm in a state where don't have to worry about inspections, so the CEL is really just an inconvenience for my son who drives the car.

Mike