Oxygen sensor problem

[dune10]

Hi guys hoping someone can point me in the righht direction.
I have a x reg year 2000 A4 1.8 petrol B5 facedlift model.
It has been regularly serviced with 73000 on the clock.
The engine management light has come on and the code is for the o2 bank 1 sensor as per the diagnostic machine.
This i found out to be the front pre cat one, this has now been replaced with a brand new Bosch 5 wire sensor to match the original.
The fault codes were removed at the same time.
It was a bitch to swap due to being seized in and also the wiring had been run in such a way it was almost impossible to get to but evetually got it done.
Much to my frustration the engine is still not running properly, missfiring slightly and the engine management light has come back on after just a few miles.
The fault codes are back highlighting the o2 bank 1 sensor and states.
"O2 sensor circuit malfunction". P0130 just as before.
It must be something other than the sensor as it is very unlikely that it is faulty from new.
I am mechanically minded but not much experience on motors so any help would be greatly appreciated on where to look next.
I would just take to a garage but was badly ripped off recently and don't know a trustworthy mechanic.
If anyone knows a good mechanic or fair reliable garage in Halifax or can help let me know,i don't mind paying but hate being skanked.
Thanks.

[dune10]

Anybody please have any suggestions as i have trawled the net without any answers.
A garage i rang that came recomended said it would be better to ring an auto electrician as it was probably wiring.
When i rang the auto electrician he said i would be better off taking it to a mechanic as it was unlikely to be wiring and he did not have any diagrams for my model??
I just think they did not want to get involved as they could not be sure what it was, the vibes i got were it was a job better left alone.
I have found that after starting it will take about 5 mins to get it so it will run anything like, in the first couple of minutes it will not respond to any throttle and wants to stall if you press the accelerator after this intial faze it will gradually clear the slight misfires and then you can drive it and it settles down.
Could it be to do with the heating side of the 02 sensor? Maybe the wiring?
Thanks.

[burkey1]

Are they VAGCOM/VCDS codes???

Post all details here!!

[dune10]

Hi Burkey, the first time the codes were checked it was at a local garage when it went in for a service and i do not know what diagnostic machine they used, i just asked them to see what it was as it had just come on.
They did not fix it but just cleared the code and added £35 for the diagnosis and told me it was PO130 B1 S1 Malfunction in circuit, a Lambda sensor fault.

I was not happy with the service as they left an oil leak on the new filter and the prices had gone up quite a bit from when the previous owner had the garage, thay also charged me for fixing a rubber boot on the front drivers side wheel which they did with a tie wrap that has since come back off again, anyway i will not be rushing back and thought i would have a go myself at changing it.

I bought an AUTEL MAXSCAN 405 for specifically for VW/Audi and when plugged in it confirmed the P0130 B1 S1 fault codes which i found out to be the front pre cat sensor.

I know these units are quite cheap but do come with a good rep and did back up what the garage had said however i appreiciate that the info will be limited when compared to the real Mckoy machines.

I cleared the codes and then looked up the part and got an exact Bosch 5 wire replacement as per my previous post, changed the sensor and ran the car for a few miles before the engine management light came back on.

The Autel gives the same fault code as before and the car has the symptoms as described.

At the weekend i may give it a longer run to see if any more codes come up providing it sounds to be running okay after the first few minutes but i don't want to run it too far if it will cause anymore problems with it not being right.

I seem to have a later B5 facelift model with small fog lamps set low in the front bumpers registerd in NOV 2000 with a 1.8 SE, 5 valve petrol engine that is not very well coverd in the manuals and thats were i am.

Like i said i don't mind paying i don't expect anything for free but can't afford to spend a couple of hundred quid to be told they don't know what it is.
I would go and by another 02 sensor just to check i havn't been unlucky and bought a faulty one but they are £76 a time.
If i could get some advise on what to look for on some of the more basic checks and by trial and error eliminate some of them it would be a start, hope this helps and thanks for asking.

[burkey1]

Have you any leaks in your exhaust system between the head and sensor?
or any leaks in vacuum pipes around engine bay?

Have a real good look here first as considering you have replaced the sensor, this could be your issue.

I would also have expected you to have a lean error code though!!

As this is a broadband sensor as opposed to traditional oxygen sensor you wont be able to measure the sensor output without proper diagnostic tools.

You can however check to see if you have 12v with ignition switched on at the heater wires.
disconnect the sensor and measure voltage across the gray+ and white- terminals of your sensor at the feed side (I.E. coming from the car).

From my understanding the module outputs a feed reference voltage to the sensor (2.6v but varies) through one set of wires, and monitors the sensor current feedback through a second set of wires. It will then convert this current to a readable voltage on your diagnostic tool
Red and black for signals and yellow for grounds I think.

At a good air/fuel mixture (14.7:1 or lambda 1), the voltages should be the same.
If the converted readable voltage is greater than the reference voltage you have a lean system, lesser and it is rich.

My guess is an air leak!

[Crasher]

“P0130 (VAG 16514) B1 S1 Electrical fault in circuit”, this could be a wiring fault or the new sensor is faulty. I had two brand new Beru sensors that were faulty not long ago. Is your engine an AEB code?

[dune10]

Engine number= AVV007193.

Also whilist i was looking through the paperwork i came across the original printout from the garages diagnostics mixed up with the bill and a breakdown of the work which has some other codes as well as the O2 Sensor.

These are numbered on the sheet as follows.

01/05. 17924-163 Intake manifold changeover valve (N156) Open circuit P1516 static no define.

02/05. 16514-035 Oxygen sensor B1 S1 malfunction in circuit P0130.

03/05. 17536-035 Fuel Trim Bank 1 (Multi) system too lean P1128.

04/05. 17545-163 Fuel Trim Bank 1 system too rich P1137.

05/05. 18010-163 Power supply terminal 30 voltage too low P1602 static no define.

From that i see 5 codes in order of when they were logged but have know idea of time scales as to when and how far apart they appear.

I have checked the wires and voltage and the colours and readings are as follows.

Wire Number 1. White = 2.992 v.
Wire Number 2. Green and Red = 0.344 v.
Wire Number 3. Green and Yellow (earth) 0 v.
Wire Number 4. White and Purple = 2.511 v.
Wire Number 5 Brown = 2.536 v.
Wire Number 6 Light blue = 0.344 v.

All measured com to terminals and black to ground on the multimeter.

I can see 3 or 4 short small bore hoses, rubber inside protected by some heat proof fibre like materials which i presume will be some of the vacumm pipes and they do look a bit worse for wear allthough i cannot see any clear holes a splits.

Is it possible to buy generic vacumm pipe or will it have to be specifically an Audi part??

I hope this extra info will help.


Iv'e something to look at now guys MUCH appreciated. Thanks.

[burkey1]

Ok, not familar with that colour coding but I checked and found out that its pin 3&4 for testing your heating element.

2.5 - 10 ohms on element and 12v at feed which also needs car running!

There is only limited tests you can do without diag tool..
You should really look at getting VAGCOM or VCDS software and cable. Abt €100 or so and its all you will ever need..

I see rich and lean errors on your original scan which does look more and more like a sensor alright..

Would be good to see whats showing up now after replacement, but as already posted it could be a faulty new one..

See doc for correct pin out...

good luck!

[dune10]

Thanks again Burkey i will check the wiring again as per the supplied diagram.
Over the weekend i have to do a bit of driving so i will give it a run out if it's not running too badly and this will hopefully get enough miles done to see if any of the other faults come back.

All for now and if and when i get to the bottom of it i will post the solution.

Thanks again.

[dune10]

Just to let you know that i have fixed the problem.
It was the MAF sensor even though the fault codes were pointing to the 02 and MAV.
Someone else on another forum had the same thing and he had fixed it by changing the MAF i did likewise and it runs much better no missfires and pulls well.
Thanks.