dpine

The 99-00 civic SI's had the 2nd o2 sensor connect to another portion of the harness (dash harness/floor harness). Does this same wiring point exist in other models (ie: EX, DX, CX TRIM LEVELs). I would like a cleaner way of wiring up my 00 CX other than the cutting and splicing method.

thanks

20civic0000si

Depends on which motor harness your using. Your hatch has both O2's on the engine harness and the SI has it on one of the dash harnesses. I just ran the four wires to the ECU, you can make it factory but you need to cut the hole in the floor and get a dash harness for an EX or SI.

dpine

Alright correct me if I'm wrong the SI still uses only 2 o2 sensors and the CX only uses 2 o2 sensors. Eventually they still wire back to the ecu in the correct pin locations. So really there is no need to add any wires to the harness if I was doing a b-series swap regarding o2 sensor wiring?

20civic0000si

yes and no... Yes they both have two O2's and yes they both end up at the ECU but the SI/EX 2nd O2 wiring comes from the dash harness because it is in the cat and on the hatches it's built into the motor harness because the case in built into the exhaust manifold. So to put a B series in a hatch your going to have to run the wires into the cabin because the B series motor harness doens't have the second O2 wiring.. Now if your running the CX or DX enginge wiring harness you may be able to plug it right in but I'm not sure if it pins out the same way on the ECU's. I just the did the same thing, I put a B16A2 w/ the SI motor harness in an DX hatch but had to run wiries for the O2.