This is a high pressure fuel pump for BMW N54 and N55 motors. The first several versions of it were junk, and failed early and often. For the N54, BMW extended the HPFP warranty to 120k miles, thanks to a class-action lawsuit. But if you have an N55 like me, sorry, no extra warranty for you!
What’s really irritating about the whole extended warranty or not nonsense, is that it’s quite literally the same HPFP on the N54 and N55 motors. Some of the earlier N55s still were built with the exact same unreliable pump as the N54s. BMW went through several revisions of the part and now they’re generally fine. But the class-action suit only covered the N54 motor, and if your VIN shows as an N55 car, BMW doesn’t warranty the HPFP past the standard powertrain warranty. Doh.
My car started randomly going into limp mode a couple weeks ago and throwing a low fuel rail pressure code. Since then, it’s pretty much going into limp mode every time I drive it. It gives you a scary message that might as well be the DANGER TO MANIFOLD thingie from the original Fast & Furious, and the car is, well, slow. By design.
About every third start or so, it takes longer to crank before turning over. These are classic symptoms of a bad high pressure fuel pump.
I actually have a couple-months-old fuel pressure sensor, that my mechanic is warrantying out just in case, but it’s likely the HPFP causing the issue. So I’m also getting a new HPFP, that I’m paying for, because BMW is all like, “nah man the N55 HPFP is all good we don’t need a warranty on those unless a lawyer makes us bruh.”
At least the new one is a supposedly revised (yet again) version that shouldn’t break. For a while.