Oil pressure is not so easy. Volvos are not prewired for them(they are electronic). Don't bother trying to get the wire harness unless you want to pull the whole engine harness of the donor (just kidding). The OEM wire goes through the engine harness and around under the crank pulley with the idiot light wire. It would be a lot of work to run it this way. I ran my wire to the passenger side instead. It works fine. You need the sender off the donor engine. If you are getting it off a B21 engine it will not fit on a B230 without an adapter.