Oxygen sensor problem

Hi! I read the fault codes from my A4 1,6 liter, and I got one fault code.
It says:

16515 - Oxygen (Lambda) Sensor B1 S1: Signal too Low

P0131 - 35-00 - -



Does anybody have any idea what might be causing this?

I checked the intake and the exhaust for leaks but it's all fine.

Thanks for any suggestions you might have.

check the wiring for the first Oxygen sensor and the sensor itself.
I think your vehicle has two, one before the cat. conv. and one after the
cat. conv.

good luck,
dave

"Loki" > wrote in message
...
> Hi! I read the fault codes from my A4 1,6 liter, and I got one fault code.
> It says:
>
> 16515 - Oxygen (Lambda) Sensor B1 S1: Signal too Low
>
> P0131 - 35-00 - -
>
>
>
> Does anybody have any idea what might be causing this?
>
> I checked the intake and the exhaust for leaks but it's all fine.
>
> Thanks for any suggestions you might have.
>
>

Hi Dave!
There is only one O2 sensor. I checked the wiring but I'm not sure how to
check the sensor... Is there a simple way to find out if the sensor is
working properly?
Thanks!

"dave AKA vwdoc1" > wrote in message
. com...
> check the wiring for the first Oxygen sensor and the sensor itself.
> I think your vehicle has two, one before the cat. conv. and one after the
> cat. conv.
>
> good luck,
> dave
>
> "Loki" > wrote in message
> ...
> > Hi! I read the fault codes from my A4 1,6 liter, and I got one fault
code.
> > It says:
> >
> > 16515 - Oxygen (Lambda) Sensor B1 S1: Signal too Low
> >
> > P0131 - 35-00 - -
> >
> >
> >
> > Does anybody have any idea what might be causing this?
> >
> > I checked the intake and the exhaust for leaks but it's all fine.
> >
> > Thanks for any suggestions you might have.
> >
> >
>
>

>From: "Loki"
>
>Hi Dave!
>There is only one O2 sensor. I checked the wiring but I'm not sure how to
>check the sensor... Is there a simple way to find out if the sensor is
>working properly?
>Thanks!

what year is this A4?
You should be able to hook up a vag-com tool (ross-tech.com) and easily tell if
the 02 sensor is working.
Also some use a digital voltmeter/multimeter and check for voltage at the 02
wiring plug with the plug still connected (backprobe). Voltage has to
fluctuate. Bentley repair manuals might tell how to do this.
Or searches on the web will give you sites like these:
http://www.forparts.com/o-21.htm
http://www.ibmwr.org/ktech/O2-sensor-testing.shtml

Your 02 sensor should be heated also, and that may cause other problems if
somehow the wires are shorted/melted. :-(

later,
dave
Reminder........
Before you criticize someone, you should walk a mile in their shoes. That way,
when you criticize them, you are a mile away from them, and you have their
shoes. Frieda Norris

Hi!
It's 1996. I hooked up vag-com to it but I don't have the correct label file
for my engine,
so I'm not sure if I'm looking at the correct measuring block. I shows a
value of around 0.5 V
and it fluctuaes... It drops to 0.0 then comes back to 0.5 and so on...
BTW I was also looking at another measuring block that is showing four
voltages.
These voltages are not the same, and they change as the RPM change,
but when I rev up the engine to about 4000 RPM they equilaze and stop at
5.100 V.
Do you know what this could be?

Thanks again for your time!

Cheers!

> what year is this A4?
> You should be able to hook up a vag-com tool (ross-tech.com) and easily
tell if
> the 02 sensor is working.
> Also some use a digital voltmeter/multimeter and check for voltage at the
02
> wiring plug with the plug still connected (backprobe). Voltage has to
> fluctuate. Bentley repair manuals might tell how to do this.
> Or searches on the web will give you sites like these:
> http://www.forparts.com/o-21.htm
> http://www.ibmwr.org/ktech/O2-sensor-testing.shtml
>
> Your 02 sensor should be heated also, and that may cause other problems if
> somehow the wires are shorted/melted. :-(
>
> later,
> dave
> Reminder........
> Before you criticize someone, you should walk a mile in their shoes. That
way,
> when you criticize them, you are a mile away from them, and you have their
> shoes. Frieda Norris
>

Hi!
I forgot to mention one thing earlier...
When the engine is cold it idles at aprox. 1200 - 1300 RPM.
After about two minutes it drops to about 860 RPM.
Is this nomal or should it be idling at 860 right away?
Thanks!

>From: "Loki"
>
>Hi!
>It's 1996. I hooked up vag-com to it but I don't have the correct label file
>for my engine,
>so I'm not sure if I'm looking at the correct measuring block. I shows a
>value of around 0.5 V
>and it fluctuaes... It drops to 0.0 then comes back to 0.5 and so on...
>BTW I was also looking at another measuring block that is showing four
>voltages.
>These voltages are not the same, and they change as the RPM change,
>but when I rev up the engine to about 4000 RPM they equilaze and stop at
>5.100 V.
>Do you know what this could be?
>

Did you introduce a vacuum leak, like the tests in those websites, to see how
the values change?

Also you may have to make sure any grounds are clean and tight. I have seen
some earlier VWs and Audis with bad grounds that stopped the 02 sensor from
functioning.

I am not sure but 5.100 V does not sound right, but are you checking this with
the vehicle in motion? I am also not sure of your FI system either! 8^)
IIRC In the USA, most 1996 vehicles have OBD-II with 2 Oxygen Sensors sensors.

later,
dave
Reminder........
Before you criticize someone, you should walk a mile in their shoes. That way,
when you criticize them, you are a mile away from them, and you have their
shoes. Frieda Norris