03_AR_CO

I bought my W12 back in early November, at the time I bought it, the B1S1 O2 sensor showed as being in fault. I drove the car back from out of state knowing the trouble and knowing this particular O2 sensor was easy enough to get at for replacement.

So about a week after having it home I had all the parts I needed to do a full tuneup/oil change. I replaced the air filters, oil filter, oil, plugs, coil packs and the B1S1 O2 sensor. Everything was fine for about 7k mi and two and a half months.

Last week the CEL light came on and the codes revealed the B1S1 O2 sensor was in fault again. I cleared the code and the CEL did not reappear until today, a week later and a good 700 miles since last cleared. I am going to mention the weather here was very cold and I did idle the car for warm-ups for much longer than normal times.

Other than a bad O2 sensor (which was an Audi O2 sensor) what could cause this failure. I have never had this sort of trouble before, and have to say I am at a loss here on this one.

Fault codes below:
Address 01: Engine Labels: 07C-910-018-BHT1.lbl
Part No SW: 4E0 910 018 J HW: 04E 090 601 8A
Component: 6.0L W12/4V G ª0020
Revision: --H01--- Serial number: AUX3Z0E5768546
Coding: 0007773
Shop #: WSC 02313 785 00200
VCID: 264812C691BAC1287A7

2 Faults Found:
008759 - Oxygen (Lambda) Sensor B1 S1
P2237 - 001 - Pump Current Open Circuit - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 7
Mileage: 79871 km
Time Indication: 0

Freeze Frame:
RPM: 527 /min
Load: 32.9 %
Speed: 0.0 km/h
Temperature: 100.0°C
Temperature: 32.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.208 V

000307 - Oxygen (Lambda) Sensor B1 S1
P0133 - 002 - Response too Slow - MIL ON
Freeze Frame:
Fault Status: 11100010
Fault Priority: 0
Fault Frequency: 3
Mileage: 79894 km
Time Indication: 0

Freeze Frame:
RPM: 1803 /min
Load: 28.6 %
Speed: 96.0 km/h
Temperature: 99.0°C
Temperature: 22.0°C
Absolute Pres.: 980.0 mbar
Voltage: 13.589 V

Readiness: 0000 1000

MP4.2+6.0

Looking up the code for PP2237 and "Pump Current Open Circuit" since I haven't come across it before, I basically translate that to a wiring or 02 issue. You can look at Bentley/AllData for more specific info. I then take the second P0133 code likely just to be a "symptom" here rather than the issue. That later code suggests something like the heating element of the O2 sensor or its wiring is defective since it needs that heating to kick in quickly. Hence without it, "response too slow." Meanwhile, I would dismiss the extended idling as relevant here; codes really are saying wiring or bad sensor to me.

You mention you bought this sensor via a dealer. By chance, I just bought the identical sensor for a simple worn out type code, but through a circuitous path first through AutohausAZ and then to Amazon, I eventually got to the right Bosch number, which is abbreviated 17177. (The erroneous Bosch listing for 17359 for position B1S1 results in a way too long cable though it still apparently functions, and 17177 actually agrees at the more detailed Bosch part number level engraved on the old Audi OE one I pulled out). I got mine from Amazon for $74 (plus tax) a few weeks back, though I see it disappeared at anything like that pretty darn cheap price from them directly and is no longer "Prime"either.

An ebay seller has one for $86 currently: http://www.ebay.com/itm/like/301088984318?lpid=82 . Note either price is like 40% of even the discounted dealer price, and cheap enough relative to the diagnostics that you may just want to try another sensor and if it proves out, return the prior dealer one as defective.

Other than that, I would look carefully at your O2 connection point up by the intake rubber duct, where all the 02 connectors are with those finicky and flimsy retaining blocks tied to the air box (and probably with broken tabs on the air box upper half?--typical from my dealer service experience). Look really carefully at the car side connector--any torn wire, broken clip lock, terminal pulled back some, etc.? Having dealt w/ that too, you can buy the car side connector housing as a piece part from a dealer, as well as an individual terminal wire which you then make a solder join with some shrink tube covering and work that new terminal into the connector. Came up because of faulty dealer disconnects previously that I later found (and similar MAF broken locking connectors actually too from air box removal to get to the filters, though they never malfunctioned). I saw a code or two tying to a ground short on my B1S2 sensor further back on the same side, which was consistent with the ground terminal issue I found on mine when I looked at it again. In your case, if you find the wiring color codes, look especially at the heating element related conductor(s) given that slow to respond code.

TSHong

I would focus on the P2237 like MP4.2+6.0 has stated. P2237 is O2 sensor positive current control circuit/open, bank 1 sensor 1. Likely there is a broken wire going from ECM J623 to the O2 sensor.

03_AR_CO

excellent information, much appreciated, I will report back with my findings, and MP4.0+6.0 appreciate the Bosh O2 sensor ID, I will definitely be looking into that, as I paid close to 180.00 from an online Audi parts supplier.

03_AR_CO

OK so here is my update, and unfortunately it is not particularly good. I purchased the Bosch O2 sensor from the supplier on eBay, interestingly the cable on the Bosch part vs the Audi part, the Bosch is about half the length of the Audi cable, this is not a problem and is actually a better fit for the location.

Drove the car less than 40 miles after clearing the codes and the CEL is back. When I replaced the sensor last night, I made careful inspection of the connector leading back to the wiring harness. All the wires seemed to be in place and seated, the contacts looked good as well. I found one wire with a nic in it and insulated it. It was not in any position to ground or short onto anything, so I was not too hopeful I solved anything with that.

So now I am in need of troubleshooting the wiring harness. Can anyone provide some guidance on checking the continuity from ECM J623 to the O2 connector. Also where do I find the ECM J623?

Also I guess it would be good to get confirmation that I am working on the correct O2 sensor B1S1 on the W12, is passenger side closest to the bumper.

Thanks in advance for any assistance here.

dvs_dave

Have you confirmed if it's one of the pre or post cat sensors?

You also mention that the replacement sensor has a much shorter cable which by default will have a slightly different resistance to the OEM part. Wideband oxygen sensor systems are reliant on fine resistance measurements. The shorter lower resistance cable may be confusing the ECU?

03_AR_CO

I am as certain as I can be that a B1S1 sensor has to be pre-cat, and as you mention I was wondering about resistance with the shorter cable, seems like a better fit, but I certainly do not know, or hae any idea what the ECU is looking for.

Thanks for your input

MP4.2+6.0

the one farthest forward that is easy to get to when you take that side's air box out.

Please post the codes again, or reconfirm are they exactly the same (two) codes as you had before that you started with in the post?

On wiring harness, you would probably have to go into Bentley to try to find it. I expect though it basically runs from that wiring block where all the O2 sensors connections are by the passenger air box through the loom stuff in the same area right to one of the two ECU's under the plenum cover right behind there. Then unless you have worked/had work done back in the plenum area, I really think about the only logical place to find an issue is right there at the connector and immediate first part of the wiring in the same vicinity. It's the only part that gets moved around in practice, and even then only with air box or spark plug type service.

BTW, for service type parts here, you can buy the connector housing on the harness side, a jumper with an individual conductor and terminal end on it, as well as a roll of the cloth type tape Audi uses if you end up cutting back/unwrapping that covering to take a further look at the little wires. I actually replaced one of the connectors when I had a broken wire (which I messed up) close in to the connector and used Audi's jumper that I soldered in a few inches back and then shrink wrapped and retaped. Since those individual terminals are virtually impossible to remove from the connector without damaging something, I basically broke or cut apart the connector housing and then just inserted the terminals (including the one I repaired) into the replacement housing.

MP4.2+6.0

both my Audi OE and my Bosch replacement for B1S1 were identical in length, after I tracked down the right Bosch part # that is (which is NOT the one most places try to sell for it). The OE cable is quite short compared to any other and is a very nice fit.

Thus, it sounds like you got the correct OE type length, and in turn if what you pulled out was longer, candidly that's a clue somebody before you probably changed this sensor before--as in, hint, this isn't the first time the issue may have been seen. Did the sensor you pulled have an Audi OE #, or just a Bosch (or some other brand) number? That would be another clue. I still have my pulled sensor somewhere if you want to pursue the #'s specifically.

And BTW, I expect no practical difference in performance electrically no matter which cable length it is. The first Bosch one I got was like 3x too long compared to the true OE, but I put it in temporarily until I got the right one. It worked and tested fine and no codes recurred. In your case, I would thus focus on the car side wiring and connector, assuming that is you didn't get a bad sensor again. Far fetched, and if indeed the prior sensor wasn't the original with some further sleuthing then its probably also suggesting a wiring/connector issue indirectly since someone played with it already, as opposed to still a sensor issue.

03_AR_CO

OK good advise MP4.2+6.0, I pulled the codes and I gotta say I am surprised that they are different, and have them posted below. I am on my way to the dealer about 50 miles away to get the O2 harness connector, my local dealer does not have one in stock.

The O2 sensor I replaced in November was an Audi part number: 1K0998262J the new Bosch branded one was 17177, big difference in the cable lengths. I found some wiring details in the Bentley, its not a user friendly manual though. Sure wish I could easily find the pinout and terminating points for the B1S1.

When I get back I am going to examine the cabling to the ECU's and check the pins also checking for corrosion.

008597 - Oxygen (Lambda) Sensor B1 S1
P2195 - 008 - Signal too Low (Lean) - MIL ON
Freeze Frame:
Fault Status: 11101000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 95233 km
Time Indication: 0

Freeze Frame:
RPM: 1227 /min
Load: 55.7 %
Speed: 64.0 km/h
Temperature: 66.0°C
Temperature: 9.0°C
Absolute Pres.: 840.0 mbar
Voltage: 13.462 V


Readiness: 0000 0000