I have been working on a swap for my car. I bought a JDM engine out of an S4 turbo 2. It was equipped with an automatic transmission. my car is an s4 turbo 2 with manual transmission.

I had originally planned to use just the core of the JDM for the swap and to attach my USDM accessories to the engine. But because I couldn't get the water pump housing off my USDM engine, I was forced to use the JDM water pump housing that came with the engine. After installing the engine, and plugging up all the harnesses again, i found something; A plug(and sensor) that my engine wiring loom didn't accomodate.

here's the pictures.


here's the male-type plug that i don't have a corresponding plug to attach with


here's the other end of that male-type plug. what i believe to be some sort of sensor. yes, that's on the backside of the water pump housing and NOT the water filler neck.


corresponding female-type plug that attaches to the male-type plug in the first picture(this is the cut JDM harness). As you can see, it's coupled with the front housing primary injector and other green-tipped plug that attaches to the back side of the water pump housing.


Now all you RX-7 guru's on this site, I would like you to tell me what this plug is for and what I should do with it. Should I just leave it alone? or should it be plugged into something else?