Could you explain a little more? What do you mean by not showing? Is this car new to you? Is it the post-cat O2 sensor? Are you positive the car isn't running software that ignores the post-cat sensors to mask carbon buildup?
If it was a normal OEM setup you would see a heater code for the disconnected heater if it was incorrectly wired. Don't think anyone has what you are looking for I have seen this question before, never seen the answer. Best I can offer you is WDS BMW Wiring Diagram System - 5 E39 from 09/98
Not the easiest to navigate, not all the wire colors but it is better than nothing.