I'm not sure if your 2016 is affected but my 2017 B48 had a service bulletin for a cylinder head ventilation hose. I had some coolant loss over the winter but after I topped a couple of times it never came back. Then I was notified of this hose problem. Dealer fixed it no charge (out of warranty) Here's a thread about it. Some others experienced coolant loss with this issue too.
https://f30.bimmerpost.com/forums/sh....php?t=1889354