[V6-12v] Trouble code 2331

[Joe - Audi]

Ron & Janet Frazier said:
> I have a 1993 100cs wagon and I have pulled the 2331 trouble code when
> the check engine light came on.  I believe this code is for one of the
> O2 sensors.  5 years ago the same thing happened.  they replaced both
> o2 sensors and that didnot solve the problem.  They did a smoke test
> and then replace the throttle body gaskets and the egr vale gasket.
> Does anyone want to venture a guess as to what is really wrong with my
> car this time.  Replacing gaskets is cheaper than O2 sensors.  The
> problem is knowing which ones without a smoke machine.  Does anyone
> have any guidance.  also, do I remember correctly that trouble codes
> are cleared one you start and operate the car after the previous
> occurrence.
>
> Ron Frazier

The trouble codes stay until you clear them manually or disconnect the
battery.

Code 2331 is "control limit exceeded" for the O2 sensor.  Are you getting
code 2341 along with it?  That is the same thing except for the other O2
sensor (one code for each sensor).  If you are only getting one, you may
have a bad sensor.  If you are getting both, you probably have an air leak
somewhere after the MAF sensor, causing a lean condition.  As before, EGR
and throttle body gaskets are a good place to start.  Vacuum leaks are
another to look for, and the EVAP valve is yet another to check.  Worst
case will be the MAF is dead or near-death (and will set you back about
$475 just for the part!).

I've got a '94 100 S sedan and am fighting the same problem.  I haven't
been able to string enough time together to troubleshoot everything yet
but, I've replaced O2 sensors (one was bad), replaced TB and EGR gaskets,
replaced *all* the vacuum lines and still have the problem.  Just leaves
the EVAP and (shudder) the MAF.

Found this link this morning.  May be helpful to you:
http://www.audiworld.com/tech/eng62.shtml

Good luck!

-Joe