The E90 guys seem to also have this issue, fixed it pretty easily by replacing the sensor. Looks like the part is is nearly every BMW from 2009-current.
https://www.e90post.com/forums/showt...acuum%20sensor.
RealOEM shows the part is #34336875605. If you want to cheap out, knockoff or used sensors are available on eBay and other sites, but there is no guarantee of them being useful. Best bet is get the OEM sensor and have assurance the issue will be fixed.
Also, the start/stop function of the car can be disabled for several reasons.
(
https://batteryworld.varta-automotiv...-does-not-work)