Okay, so I have an LX wiring harness. I bought and installed it myself when I purchased the car. So the LX oxygen sensor plugged into the harness and installed into the LX manifold without issue. I have a new oxygen sensor coming in the mail. I will probably splice it to fit the harness and hopefully have the correct manifold on there by then.

I have an LX ECU. I've taken it out and inspected it before.

The car has never had the VTEC hooked up, but that is a future project!

I believe I will be splicing in the new O2 sensor when it arrives. I've decided to also try and get the correct exhaust manifold and downpipe and of course a new gasket. Will update in a while.

 

Because the EX has a 4-into-2 manifold, then a 2-into-1 downpipe; the O2 sensor is located under & behind the engine (where all the exhaust finally connects into 1 pipe).