Oxygen Lambda errors

[Old Navman]

Guys:

Anybody can shed some light as to what's happening with these error codes and where exactly is the B2 S1 bank situated. Thanks in advance. The error codes are below:


oxygen lambda sensor signals swapped
p0040 B1 S1 / B2-s1 intermittent

freeze frame:
rpm: 624
load: 21.6%
speed: 0.0 km
temp: 73 C
temp: 35.0 C
absolute pres: 1000.0 mbar
volatge: 13.970 V


fuel trim Bank 2
P0174 001 - system too lean
freeze frame:
rpm:1340
load: 65.1%
speed: 55km/h
fault frequency: 2
temp: 74.0 C
temp: 16.0 C
absolute pres: 1010.0 mbar
voltage: 13.097 V


Oxygen Lambda Sensor B2 S1
P2197 signal too low (lean)
freeze frame:
rpm: 1620
load: 54.9%
speed: 75km/h
fault frequency: 1
temp: 80.0 C
temp: 9 C
absolute press: 1010.0 mbar
voltage: 13.843 V


Post catalyst lambda sensor correction
p2099 too rich - intermittent
freeze frame:
rpm: 2044
load: 43.5%
spped: 59 km/h
fault priority: 0
fault frequency: 1
temp; 84 C
temp: 13.0 C
absolute pres: 1010.0 mbar
voltage: 13.970 V

test mode 07: pending emission related fault codes
address 7EB: 1 fault found
P2234 - oxygen lambda sensor B2 S1: signal shorted to heater circuit

[Old Navman]

Nearly 50 views - is there anyone??? - kamold? -that can answer at least question regarding the location of that B2 S1 sensor/s: Looking at the front of the car left/right ? upstream/downstream? 2/3/4/5 wire sensor? Possible part/OEM part number? It would be very helpful to me as the car is currently running rough and using +3 litres /100km more petrol but I have to (for now) use it to get to work.

[Passat my07]

I think s1 will be before the cat. If the heater coil has a short to earth it’ll need replacing.
They should really be replaced as a pair anyway.
If you want to work out which is which you could disconnect one and check the fault codes again.
You may have other problems too though like a vacuum leak, faulty pcv or build up on the inlet valves?

[Old Navman]

I think s1 will be before the cat. If the heater coil has a short to earth it’ll need replacing.
They should really be replaced as a pair anyway.
If you want to work out which is which you could disconnect one and check the fault codes again.
You may have other problems too though like a vacuum leak, faulty pcv or build up on the inlet valves?

Thanks Mate, that sounds quite serious. Those regulating probes, in front of the catalyst are quite expensive - I think about $250 each. If I had to change both that's big bucks. The car is running rough but only started like that after the engine light came on. Wouldn't a PCV valve issue manifest itself rather slowly over a period of time? - I'm hoping as to do the PCV is probably at least 3 x times as much as the 2 regulating probes.

[Passat my07]

I think I read on here that you can buy just the pcv diaphragm aftermarket.
Once the diaphragm breaks it’ll start running rough quickly. You still need to diagnose it first though.
You also have that p0040 code. Has anyone mucked around with the exhaust or the o2 sensors? If they are around the wrong way it’ll add/remove fuel from the wrong cylinders.

[Old Navman]

I think I read on here that you can buy just the pcv diaphragm aftermarket.
Once the diaphragm breaks it’ll start running rough quickly. You still need to diagnose it first though.
You also have that p0040 code. Has anyone mucked around with the exhaust or the o2 sensors? If they are around the wrong way it’ll add/remove fuel from the wrong cylinders.

Yes, I did see the post by Ian and the youtube video on how to get to the PCV but I think that was on a 2L engine not the V6?
Edit: the video was on V6 engine but only relevant to R32 Mk5.

No, nobody has touched the exhaust. I got the front end bushings done including the sub frame bottom engine mount bushes. But as I had to order the single use TTL sub frame bolts from VW (they had none in stock) I had left the splash shield off. It's been raining here heavily and I'm wondering if leaving the splash shield off could have somehow affected the sensor probes?

[Old Navman]

So, I at last I managed to get both the upstream sensors replaced. It wasn't that difficult once I gathered all the parts and information about the job. I'll describe this below hopefully for the benefit of another poor soul that doesn't know how to do it but wants to persevere with self-repair.

First, disconnect MAF sensor cable and reposition the steel clamp which clamps onto a hose connecting air filter/MAF to throttle body.

Second, take the 8? screws which hold the top cover of air filter. Once you get that off and remove the air filter element you will see 3 hexagonal bolts sitting in the middle of a kind of rubber bush on the bottom of the air filter compartment. From memory, 2 are hex 5? 6? and 1 oddly enough hex 4. Once you undo those, you might be able to pop the air filter bottom compartment out.

Additionally, I disconnected and removed the air intake element in front of the air filter/MAF assembly. Once you have removed the above you should have enough space to do the actual job.


1. Air filter removed

Remove the 2 x O2 sensor connectors from their cradle and disconnect them. I marked mine beforehand but they should be colored - black to black (AM) and black/brown to brown (AN).

2. MAF sensor connector marked yellow, O2 sensors and sensor cradle red

Fit the oxygen sensor wrench (first onto AN sensor) by placing the mouth opening onto the thinner part of the connecting loom (near the top of the connector) and trace it down to fit onto the sensor hex part. If you haven't got O2 sensor wrench try using ring spanner, open end spanner or adjustable spanner. If you're unlucky and your sensor is really stuck you might have to spry WD40 or something similar to get it loose. It might take a number of sprays to get it loose. You might also have to wait 20-30 min before it let's go.

Next, with the first sensor gone try the same on the AM sensor. In my case my O2 sensor wrench wasn't really good (for the AM sensor) because there was no space to turn it. Instead I used a small adjustable spanner and was fortunate that both of the sensors were not done up that tight.

3. AN sensor removed


4. Both AN & AM sensors removed


5. New and old - the old sensors both sooty black from running too rich.


6. Old sensors


7. New sensors fitted

Once everything was back together, new sensors fitted and connected I deleted all the fault codes, prayed and went for a drive. The MIL light did not come back on HOWEVER at this point in time the fuel consumption (option 1) is still in the range of 8.5l/100km and after 4 longer runs it should be down to around 7.2l/100km. Maybe there is another problem which is not evident after another scan.

Ok, that's my bit for today.

[prn31]

Thanks for providing such a comprehensive guide to replacing the oxygen sensors. Do you have part numbers and their cost? Where did you source the sensors from?

Regarding the PCV replacement, Ian's video is for an R36. I've done this job and it isn't too hard as the R36 has a two piece inlet manifold.

[sn809]

Top job mate, thanks for putting it up with the pictures.
Have u checked the fuel pump and more relevant is it still driving rough?
If not it could just be taking a bit longer to adjust.

[Old Navman]

Thanks for providing such a comprehensive guide to replacing the oxygen sensors. Do you have part numbers and their cost? Where did you source the sensors from?

Regarding the PCV replacement, Ian's video is for an R36. I've done this job and it isn't too hard as the R36 has a two piece inlet manifold.

I got the sensors from Aliexpress but I found that for later model VW's, say 2010-12 onwards, generally the sensors were more readily available. So there were plenty of those on "the bay" from US, UK as well as China. The sensors for my car are (upstream) OEM 022906262AN and 022906262AM but my choices were either to fork out $420ea from VW, $250ea from one Oz site and at the extreme end about $80ea from China. Of course those prices were only for the parts and did not include the fitting.

For my car the European shops appear to have plenty of stock but they mainly deal in Bosch, FAE, Metzger, Vegaz, NGK. They also sell this brand Meat & Doria. I suspect though these Meat & Doria are same Chinese sensors which I could buy on Aliexpress the difference being I could get them directly from China at about 1/2 the price.

Regarding Ian's video - I did have a look but found that on my 2006 B6 3.2Lt engine the manifold bolts layout is different to R36. Also I think 3.2Lt engine manifold is not a 2 piece manifold. It looks like to take it off one needs to take the grill/bumper bar off? etc, etc. No wonder VW charges about $1400 for the job. I wish there was a video on 3.2 engine as PCV is the next thing I have to have a careful look at.

[Old Navman]

Top job mate, thanks for putting it up with the pictures.
Have u checked the fuel pump and more relevant is it still driving rough?
If not it could just be taking a bit longer to adjust.

No, I haven't checked the fuel pump. Would a problem with fuel pump show up as an error on VCDS? Recently I've been getting this intermittent error " Low pressure fuel regulation" P310B - 004 fuel pressure outside specification"

Other errors lately have been "Post Catalyst oxygen lambda sensor correction bank 2 P2099 - 001 too rich". Don't tell me the downstream sensors are failing now! I'm hoping though this was as a result of the upstream B2 S1 failing but I haven't scanned the car for errors since the AN & AM replacement.

[sn809]

Well you could use vcds to check function of your pump. In a diesel its used to prime the fuel system after a filter change and using the prime function causes it to pump fuel through.

Often all of the sensors have to be changed, probably the ones in the back have a similar soot content on the surface. If you have the tools and skills you may as well give it a go.

PS I am not a mechanic just trying to help out based on what I read about a problem on my own car which was a diesel.

[Old Navman]

Well you could use vcds to check function of your pump. In a diesel its used to prime the fuel system after a filter change and using the prime function causes it to pump fuel through.

Often all of the sensors have to be changed, probably the ones in the back have a similar soot content on the surface. If you have the tools and skills you may as well give it a go.

PS I am not a mechanic just trying to help out based on what I read about a problem on my own car which was a diesel.

No worries, thanks anyway. Well, yes the downstream sensors being of similar age are probably due for replacement. As to the pump - I did read somewhere about testing/priming diesel pump using VCDS but I'm sure there is an option to test the fuel presure sensors in petrol angine as well.