Random stalling at lower speeds - Surging at higher speeds

[Ricky Bobby]

Two random issues going on and wanted to document in case someone comes across -



Bone stock 82k miles 2013 X5D -



This one is actually scary enough to my wife that the car randomly stalls/shuts down while driving and its usually coming off of a stop or at lower speeds - happened once on the road today and once in a parking lot and then once as well by our mailbox - she is going to park the car for now -


I drove it this morning and around 50mph in 5th gear the car surged as if it was skipping a beat -


Hooked up to ProTool and only codes showing are in the DME:
3E90 - Crankshaft sensor, signal
48DC: Boost pressure sensor, plausibility


I am assuming the crankshaft sensor is going and showing me symptoms but wanted to be more assured before I order one - I have a long list of maintenance items to address in the coming weeks.


I know the crankshaft sensor is at the back of the engine and I believe the starter has to come out which sucks.


I don't know how to check or where the 'boost pressure sensor' is - although with the plausibility code I really don't know if thats the issue.


Been a long time guys but with a 2 year old now its imperative we keep the wife's car running great.