MP4.2+6.0

Go for the car side connector, or actually what is the wiring leading up to it. Given you changed the sensor, but still have a connection type code, that most likely puts it in the wiring. The individual conductors that lead to the connector are small enough they can be prone to internal breakage or other issues.

After I went through this drill on mine, I finally bought a set of the pre-made connector jumpers and new plug from audiusaparts, plus some all in one heat shrink tube and solder splice connectors. Cut out the connector a few inches back--where the (small conductor) wiring could still get broken due to repeated movement or stress. I spliced in the new jumpers after threading them into the new connector end, used a heat gun on the pre fab connectors to melt the solder and think the tubing cover all in one step, and taped it up with some black cloth tape. Presto, no more codes ever since.

Although I had forgotten it at the time, there is actually a W12 specific TSB for 2005s and 2006s that covers exactly this connector/wiring issue, with exactly the same fix path as I eventually went down after eliminating other scenarios like the particular sensor. The TSB said it was corrosion at the wire terminal connectors. What ever it was, mine was cured.

Avdwaal1

Awesome, I am going to do that. Do you happen to have the part numbers at hand?

Arthur

MP4.2+6.0

The conductors/wires are: 000 979 133 AB You need three of them, if you cut each in half. Each one comes with the identical connector factory crimped on both ends of a conductor about 18" long. They were each about $12 from audiusaparts about three months ago.

Connector: IF it is brown colored: 1J0 973 733A They use both brown and black connectors on the pre cat sensors that are identical except for color. Thus be sure to get the right color to maintain the color coding. The post cat O2 sensors use a different connector with fewer terminals. Connector housing is about $10. Now that I look at a picture I took at the time, I remember the conductors go in from the back so you can do all that prep first. Then you push them in and they lock, plus there is a horseshoe shaped blue plastic retaining clip you remove from connector before putting the wire terminal ends in, and then you re insert that retaining clip to really hold them in place forever.

The butt connector I used, via Amazon: These are pretty cool for wire work. First time I used these and they really were simple and all in one. Hardest part was simply you kind of needed three hands, or an assistant. I went with the assistant. One holds the two conductors in the connector carefully while the other activates the heat gun--without cooking the boss' fingers. For belt and suspenders, I had also left a piece of heat shrink tubing on each conductor before I used the Tyco connector. So as step two I heat shrank that tube over the solder connector. I wanted as close to zero chance of an issue with this in the future as possible.

When I did it, I staggered the splice points slightly among the six conductors; helps make overall bundle smoother. Also be sure to keep track of which color wire goes in which location in the connector. I first cut them near the connector so had little to go by. Should have cut them at least an inch back. But I drew a diagram I could use to double check/remember, plus I took a (separate) camera phone pic of it to start. I have factory Audi cloth harness repair tape; I bought it years ago now--lasts a lot of jobs. Pricy. But to get pretty close, you also still buy old school "cloth friction tape" from years ago now before electrical tape went from cloth to vinyl. Type that into Amazon if you want to go that way. With a good tape job and match, no clue harness was ever even touched. As I said, 100% solution on mine after one replaced sensor still threw a random faulty connection code occasionally.

Avdwaal1

Thanks! I found these using your part numbers on ggle: Wideband Connector | VEMS US
comes with wires!

03_AR_CO

I read through this thread, and would appreciate any input for what I am seeing on my W12.

I just replaced the B2S1 O2 sensor, and have the following codes returned:

Address 01: Engine Labels: 07C-910-018-BHT1.lbl
Control Module Part Number: 4E0 910 018 J HW: 04E 090 601 8A
Component and/or Version: 6.0L W12/4V G ª0020
Software Coding: 0007773
Work Shop Code: WSC 02313 785 00200
VCID: 264812C691BAC10E24-8072
1 Fault Found:

008768 - Oxygen (Lambda) Sensor B2 S1
P2240 - 001 - Pump Current Open Circuit - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 162016 km
Time Indication: 0

Freeze Frame:
RPM: 1403 /min
Load: 41.2 %
Speed: 59.0 km/h
Temperature: 77.0°C
Temperature: 36.0°C
Absolute Pres.: 840.0 mbar
Voltage: 12.573 V


Readiness: 0000 0000

I am about to dig into the wiring, would appreciate any opinions on the cable plant, I am thinking there is a break or weak connection to the pump circuit (yellow wire on the car side O2 connector).

MP4.2+6.0

Yep, been there, seen that, done that. Same basic code. Same first tried the sensor but back the error came. Used the Audi wiring jumpers spliced into car side harness as already mentioned, plus a new end connector. Definitive end to code, literally never seen again.

richard-tx

Vinyl electrical tape first came on the market in the 1940s. It was pretty poor stuff and then 3M made the first good vinyl tape in 1946. The off-brand vinyl tape is crap. Another issue is the application of vinyl tape. Very few people know how to properly apply vinyl tape.

Weatherproofing splices has always been a challenge. The best old-school splices I have ever encountered was a two step process. The first step was to use a rubber based "tape". It was soft, flexible, and molded quite nicely to the splice. Then it was wrapped with vinyl tape to keep the rubber from sticking to everything. 50 years later, the splice was clean and dry despite being in a harsh marine environment.

In modern times heat shrink is excellent and beats all tape methods but finding the correct tubing is a challenge. It is labelled glue lined. The hot melt glue makes a waterproof and dustproof hermetic seal. This is what GM/EMD uses on their locomotive traction motor cables.

As a side note, all of the wires and cable on a locomotive, including the generator cables and traction motor cables are crimp spliced...never soldered. Why? A good crimp is a gas tight connection. With a life expectancy of over 50 years on a locomotive, the reliability of a properly crimped terminal has been proven. The problem is that not everyone knows how to properly crimp a terminal and uses the correct crimping tools.

In the end, glue lined heatshrink tubing installed with a heat gun is tops.

the_duke

+1 on the glue lined heat shrink tubing. Good stuff.

Mister Bally

Love those locomotive generator and motor ring terminals. Some are the size of my old VW Beetle engine!

MP4.2+6.0

There are two different elements to the repair. One element is using the Tyco connectors that have both the built in solder and the heat shrink outer jacket. In the links I cross referenced IIRC. All one step and then also pretty well sealed already. The second step is really just the cosmetic of wrapping the wires. Audi sells the tape if you want OE look. One (overpriced) roll lasts me 5 or more years. Sort of a cross between friction cloth electrical tape and bicycle handlebar tape; very sticky, thin for workability, and does not tear without basically scissors or a knife to cut it. Cosmetically all are pretty close when new. If you wrap it well, it is better sealed than the OE loom, which is really just the same sort of tape would around the conductors and often not a good seal at the connector ends to start with. The whole set up is behind the passenger airbox on a W12 and about a foot above the exhaust manifolds. Gets plenty of heat drying, every day.

Agreed on the vinyl tapes. Only the branded stuff like 3M holds up in my experience. In this case the various cables for the connectors (8 of them!) are are somewhat visible, hence the cloth OE approach I used.