I must preface this with the fact that while I have quite a bit of automobile experience, I have little BMW-specific experience.

That said,with those codes (current too high, voltage too low) I would first check the wiring and connector for a short, e.g., look for any place the harness might be touching something and wearing through. I believe the wires for this come out of the valve cover.

Additionally, you could tug and push on the wires gently to see if it makes the problem go away -- if it does, you probably have a problem inside the harness and could open it up and examine the wires.

It could just be a bad sensor, but that combination of codes points to a short, IMHO.

Perhaps someone with more experience can chime in with more specifics and/or an alternative course of action.