I've recently purchased a 1997 Civic SI coupe with a B18 swap that was thoroughly abused by its previous owner. Currently I am trying to find the connector for the downstream O2 sensor on the harness. Would anyone be able to point me in the right direction as to how to track it down? Ive looked under the car where one would expect it but no luck.

 

welcome to the forum the normal downstream o2 sensor connector is located under the a/c condensor can.up front right. hooked up just after the Cat. how did the previous owner get smog done, does the b18 have headers, what year is the engine, does it have a cat. you have limited info, difficult to answer your request. sorry

 

I posted a reply with some photos and details. It is awaiting moderator approval

 

Since it appears that it is taking a while to approve my images I have found 2 4 pin connectors on the drivers side in front of the motor alike the upstream connector with

• brown
• brown
• black
• brown/black

and

• white
• red
• blue/red
• blue/white

wires respectively

 

O2 sensors usually have four wires
One pair is for the heater circuit
Another pair is for the O2 sensor signal
Usually, two white or two black wires for the heater circuit
And any combination for the O2 sensor signal
I just do not know

 

I think I may have found it. There is a 4 pin connector under the center console with 2 black and white wires, a red and white and a green and white.

 

Does any of the connectors look like it will fit the O2 sensor?
Hopefully it is the right one?
Good luck