2002 A6 3.0 Quattro ...These sensors are located just under the fire wall. This would be my foward sensors before the catalytic converter....I have talked on the phone with my dearlership and also with Autozone ..both tell me that my sensors are five wire.. Now Ihave this sensoron my desk as I type and itis a four wire sensor.Would anyone have any idea on this.. I cant take the part number of it right now because I cant find my glasses but any thoughts would be helpfull..

 

If the connector on it is black, it should be a front one. If its another color, its probably a rear one. Thats for factory sensors. The connectors for the o2's are cliped to the firewall on the car. In any case the front o2's are a pita. The ones you can see from the top off the back of the engine are the rear o2's.