Hi Everyone,

I'm new to forums so bare with me. Here's the issue:

I just bought a 1999 Civic EX for my girlfriend from a private party, and unfortunately missed a few things while inspecting it. It appears that the entire exhaust was replaced (including the manifold) by an amateur.

It failed emissions because the visual inspection revealed that two oxygen sensors were not connected: the wires are physically cut and dangling from the oxygen sensors before and after the catalytic converter that is integrated into the exhaust manifold.

The strange thing is, the car has a second catalytic converter located under the center of the car, with another oxygen sensor which is connected. And, I for the life of me, cannot find any connectors or cut portion of wiring harness where the two unconnected sensors should be connected.

So, I'm wondering if it's possible that this exhaust manifold came of a different car at a junkyard, and originally the Civic EX didn't have 3 oxygen sensors. The engine is stamped "DI6Y8" and the exhaust manifold has "8A19" on the left side, and "G A1" on the right side.

Thanks for your time,
Wade

 

it should have 2

 

Thanks for the reply. Are you sure that it should have two? Does that mean that 3rd oxygen sensor in the center of the car is not original?

 

for obd2, there's a pre-cat o2 sensor and a post-cat o2 sensor, thats it

 

It should have 2, one in the exhaust manifold and 1 in the cat under the car.
Correct me if im wrong but the y7 manifold has the cat in it so you have the y7 manifold on a y8. You need the y8 manifold and the cat underneath your car.

 

2

 

typically, it would be on the downpipe of the header, then after the cat converter. your exhaust on a ex (d16y8) should go header, downpipe, cat, midpipe, tailpipe, muffler. if you have a cat on your header, someone either swapped the motor for a d16y7 or the manifold for one off of a y7. maybe pics would help?