2016 BMW X3 - weird warranty

In Sept got Drivetrain Malfunction warning and shop put in new diesel fuel filter, which was needed (had 42000 miles), and code justified. Got another code warning three wks ago and then shut.down in traffic last wk (did start and run fine after setting for 1 min). At the dealer now … they thought fuel pump going bad (warranty covered) but now fuel rail system needs replacement (non warranty) after recheck.
The 2016 x3 diesel only has 46000miles on it. You would think an inter-engine problem should be warranty protected at that mileage…??

Read the warranty. It should be in your gold box. Look for the power train warranty and see how long it is (age, mileage) and see what is excluded. If they said the fuel rail failed because of misuse, including bad fuel, it may not be covered. Tell us what the power train warranty says.

4yr/50,000 mi warranty on the powertrain from when the X3 was put into service.

What part of the fuel rial needs replacing?

The warranty on a BMW is 4 years/50,000 miles. There are specific parts covered for 7 years/70,000 miles in the state of California.

If this vehicle was purchased before December 14, 2016 the basic warranty has expired. A 2016 vehicle can be more than 5 years old at this time.