Sir that there is the pressure sensor for your HPFP. You have two fuel pressure sensors. One is the low pressure sensor on the feedline going into the back of the pump, then the high pressure sensor is the plug you see on the pump itself. I'm surprised you don't have a check engine light (you didn't mention having one) for this being unplugged (or that the vehicle ran at all with this unplugged!).
Here's a RealOEM link for your reference:
https://www.realoem.com/bmw/enUS/sho...diagId=13_1355