[s-cars] Re; not the code I expected

[Tom Green]

There is a lot of information about O2 sensor codes in the Bentley and
many troubleshooting tips.  It is important to understand that most  
codes
are not a direct indication of the sensor condition but a secondary  
result of
some other problem.  Anything that causes excessive or insufficient  
amounts
of fuel in the system will exceed the limits of the O2 sensor  
adjustment and
should result in a code and MIL.

And, no, the O2 sensor will not prevent the engine from starting.

At the point that the engine does not start, if it is a faulty CPS, it  
is not
intermittent at that point.  If the MIL was on when you shut down (and  
it was
caused by an open or short in the CPS) you would expect a code.

I am not sure about the blink codes coverage, but it's better than  
nothing.
The VAG-COM will give you more information about the fault.  Right now
you don't know if the fault is rich or lean.  Bentley also indicates  
the MIL
will be on when this DTC is present.  Is there a VAG-COM available in
your neighborhood?  Have you observed the MIL on when driving the car?

Because the symptoms closely match the CPS failure syndrome experienced
by so many listers, you may have started down this path to the  
exclusion of
of other possible causes that do not have a specific DTC, i.e., fuel  
pressure
or supply.  Perhaps you have had some clues, i.e., poor mileage that  
have
not been resolved?  I did not understand your other comments about ....
overheating and other assorted comments in the Bentley??

You can verify if a CPS fault will record a code by unplugging the  
sensor at
the front of the fuel rail while the engine is running and then  
plugging it back
in.  That might eliminate a little guessing even if it is not totally  
conclusive.

Tom

> -----Original Message-----
> Date: Wed, 23 Sep 2009 23:09:45 -0500
> From: "Steve Marinello" <smarinello at entouch.net>
> Subject: [s-cars] not the code I expected
> To: "'S-Cars'" <s-car-list at audifans.com>
> Message-ID: <8613DE88AA7A4D0AB99112860184A19B at GT5674>
> Content-Type: text/plain;	charset="us-ascii"
>
> Well, the S6 has failed to start one more time.  It was warm.  It  
> restarted
> after it cooled off a bit.
>
> Finally blinked the codes, expecting the cam sensor, if anything.   
> NOT.  Got
> 2341; oxygen sensor..overheating and other assorted comments in the  
> Bentley.
>
> There was a new sensor put on in the Spring, along with two new  
> cats.  As
> you may remember, I was frustrated that the sensor was bad, because  
> the
> mileage did not improve and, in fact, got worse.  My mechanic  
> checked the
> sensor and said it was functioning fine.   Hmmm.
>
> Would the O2 sensor even keep it from starting?  Which way to go  
> now?  I
> suppose the first step is to check the current CPS and see if it is
> functioning, but since it's intermittent even when hot, that may not  
> show
> anything.
>
> Let me know what you think.
>
> TIA,
> Steve