Top left where it plugs in

 

I think that is your oxygen sensor hookup. The other side is coming out of your catalytic converter.

Ricardo

 

Ditto, oxygen sensor plug.

 

Looks more like cruise control to me.

Marc

 

Here's my O2 sensor plug

 

Thanks guys I think that's exactly what it Is!!

The p.o. did not have the relay up front for the catalytic converter (R44 of I remember correct)

He also had this o2 sensor unplugged. This is leading me to believe he did a cat bypass, or something similar.... do you all agree?

 

My bad - you're right.

The cruise plug is also round and in that area but is a 7-pin.

Marc

 

Yeep - o2 for sure

 

Since a 964 is OBD1 the O2 sensor is upstream of the catalytic converter's filter element, so a bypass wouldn't have an effect on the O2 sensor's readings...unless he just replaced the cat with a piece of straight pipe with no O2 bung in it, but that's a pretty intricate part of the exhaust system with flanges, slip fittings, brackets, etc that isn't very DIY friendly.