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Discussion Starter · #1 ·
There's no such write-up, info in the forum so I thought I might give a few pointers that might benefit someone down the road as long as these cars are still moving.
If you have access to a shop lift, bless your heart. Otherwise you have to raise the car as much as possible so you have enough room to move under there. Since I still don't have yet a cement floor in the garage, I chose the lazy way to just drive it on ramps. If you are a big person, forget about it - raise it on jack stands as high as you can. If doing the job on your own like myself, then count of crawling under the car and back out numerous times...
An easy way would be to cut the sensors' barrels after removing them and just pull the wires through the engine bay, but you still have to thread the new sensors. The easiest way to remove the passenger side sensor (referred to as B1S2) is with a open end 7/8" or 22M wrench. Forget about the "lambda wrench". While you can fit it over the barrel after some contortions of your fingers (skinny hand), forget about any idea of turning it. There's no clearance anywhere, no matter how hard you try. The 7/8" wrench worked just gr8 for me.
UI haven't taken too many pics, but I'll try to list the steps in an orderly manner.
1. Drive the car on ramps or raise it as high as possible and secure it on some sturdy jack stands. (safety, safety, safety, right?)
2. Pop your hood.
3. Remove the small cover over the purge valve/Maf sensor area
4. Remove the air intake section between the Maf sensor and intake duct
5. Remove the air intake duct - you need to undo the bolt holding the vacuum plate onto the air duct and the bolt holding the air duct itself
6. Now you have some room by the firewall area. Locate and undo all the connectors on the firewall: B1S2 sensor (mine had green connector/s), B2S2 sensor (mine had Brown connector - well, it had, I had to replace it), B1S1 sensor (Black connector), and Knock Sensor Connector (Orange), you'll work just with the leftmost two: Green and Brown. You remove the others so you can move the wire loom out of the way, gives you more room and some visual clearance of what you're doing. You can also pull out from the triple-plastic clip the purge valve hose + the A/C hoses. Pull that plastic clip off (it has two little tabs on the back you have to squeeze and push them through. Now you have more hand clearance to work with the connectors (if needed).
7. Make sure you mark or make a mental note of each connector belongs to what sensor. It is time to get under the car. The B2S2 sensor comes off easily, there's plenty room and the lambda wrench works w/out problems. As mentioned previously you have now two options: a) cut the sensor barrel and thread the wire out from the engine bay, that's the easy way, right? Not so fast... b) tie a wire onto the sensor' barrel and onto the connector of the new sensor that you bring under the car (the connector has a channel that slides into the holding bracket on the fire wall; that's were I tied the wire). Go to the engine bay and start pulling. As the old sensor comes out, the new sensor connector comes with it... You might need to get under the car several times until the connector clears the tight area between the center differential's top and the heat shield above it. Leave underneath just enough slack that allows you to tighten the new sensor in. You can pre-twist the sensor's wire from the engine bay area (well, the best you can do) in the direction of tightening (clockwise) to prevent excessive bending of the wires when tightening the sensor.
You're done with one sensor.
It would be smart to start with installing first the B1S2 sensor before installing the other. That way you don't have extra clutter to squeeze your already tight working place. You can barely fit the edge of the hand in there to put two fingers on the sensor to start it threading in the hole.
8. Repeat for the other sensor.
9. Now you should have both sensors' connectors into the engine bay. You don't need much slack underneath, so it's safe to pull into the engine bay as much of the wires' length as you can. Secure them as the other ones were, or use a tie wrap and tie'm around something away from a heat source.
10. Install everything back in reversed order.
Extra note: The new oxygen sensor's connector did not fit the old connector in the look (the brown one, so I had to replace that connector with the new one provided in the Bosch' sensor box. I purchased mine from FCP Euro (thank you) for $ 67/piece.
I'm lucky that I have a Schwaben set of connector wire pullers. It finally came in handy after 7-8 years of gathering dust... You may have to do the same, or you may not. I'll try to insert some pictures, although it is late already and I feel like I've been hit by a train.
I hope someone finds this helpful at some point in time. It is a pretty bitchy job, but with patience you will come through.
Happy wrenching. :wrench: Imgur: The most awesome images on the Internet


- Old connector:

- New sensor connector:

-Connector Tool Set

- Wires out:

- Wires back in the new connector:

72 Posts
Chefro, you have been a God-send describing the steps you took to replace the oxygen sensors. I have been searching for a while for either a YouTube tutorial or similar to help me tackle a sensor replacement on my Passat v6. It does appear a daunting task, say, in comparison to doing a timing belt change or axle replacement, both of which I have done in the past 2 years. The Schwaben wire puller tool kit sounds like a good investment which I will look up. Thanks a million. Would you mind if I mention your write up on other related forums?
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