O2 sensor condition

["Lino M. Valadas" <valadasl@osha.igs.net>]

Hello fellow Audians,

I've been following with interest the O2 sensor thread.  
It has made me wonder if my O2 sensor should be replaced.  
I have tried (unsuccessfuly) to determine its condition.

The thing is probably gone (10+ years/182K Km), but how can I tell. 

Today I decided. What the heck, disconnect it and see what happens.  So I
did.  And nothing happened.  It was cold outside, the car started the same
way it always does.  Drove about 12 km at different speeds (the way home
from work) no difference at all.  Observed my fuel consumption, it actually
dropped from 12.8 to 12.7, (a drop is good for l/100km).

I have the three wire one.  I verified that I have power to the heating
element.  I could not measure any voltage at the wire to the computer. (my
voltmeter is only sensitive to .1 volt).  The sensor's heating element had
resistance, so I assume it is working.

The big question is:  Do I buy a new one?

With a new one:  Will I notice any difference in the engine's behaviour? 
Will it improve my fuel consumption (I used to get 11.5 at one point,
better than the current 12.8 l/100km).
Any comments would be appreciated.

TIA

Lino

865ktqw