On my current road trip to Nashville, then Orlando, my car broke down 25 miles shy of Nashville. I have had a JB4 installed for about 7 years, and a P3 vent gauge installed. After 9 hours on the road (about 6 in heavy rain, 18 January), the engine started misfiring. I saw the half engine graphic. Pulled over and restarted the car. I continued but the misfire came back quickly. The misfiring worsened until the car would no longer run. The P3 unit showed codes that all my injectors had failed.
I was towed to the BMWDealer in Nashville and with about an hour left on the Saturday afternoon shift, they diagnosed a failed high pressure fuel pump. That was Saturday. Today, Monday, they were able to get a new pump installed. But the car won’t fire. They found water sitting in the DME/ECU, and that was all shorted out. The SA thought that the DME damage probably caused the fuel pump to go.
They are ordering a new DME unit - should be delivered tomorrow, and installed. Hopefully, no other electrical damage.
The JB4 is coming out (sorry to hear - it’s been a good unit to aid everyday driving).
Bottom line: The Dealer estimate is just now north of $4k.
167k miles, old school preventitve maint. Trouble free since new. Does not use ANY oil. No need to add more lingui-moly between 7k mike oil changes.
2008 535i N54. Build date March 2007. Purchased new. Went through the early days of HPFP failures - mine was replaced in 2009 under warranty.
Wife asked about the value of the car for trade in..Said I was not interested.

Cheers, while awaiting repairs in Music City.
Neubs