BMW 5 Series Rough Idle & Stalling, Rail Sensor Issue?

Hey there! I have some experience working on BMWs. I had a similar issue with my 2003 BMW 3 series (coming from a 5 series family too). Mine had exactly those symptoms, rough idle, RPM jumps, and poor throttle response. After scanning, it turned out to be a faulty fuel rail pressure sensor. My trusted mechanic replaced it, and it cost me around 240 Euro including parts and labor. The car's been running smooth since then. Before I share more specific advice, could you share: Have you scanned for error codes? Does the issue get worse when the engine is warm? What's your current mileage? These details would help me better understand if you're dealing with the same problem I had.

Thanks for your detailed response! My car has 111658 KM on the clock and yes, the issue does get worse when the engine warms up. I did get it scanned at a local shop but they weren't very clear with the codes. Your experience sounds exactly like what I'm dealing with, especially the RPM fluctuations. That repair cost sounds reasonable compared to what I was worried it might be. I'll definitely get the fuel rail pressure sensor checked out. Good to know it fixed the issue completely for you!

Hey again! Glad to hear back from you. Yeah, based on what you're describing, especially the symptoms getting worse when warm, it's sounding more and more like we had the exact same issue. My BMW actually had around 115000 KM when this happened, so pretty similar to yours. I remember being really worried it was going to be something major, but the fuel rail pressure sensor was a relatively straightforward fix. After I got it replaced, all those annoying symptoms, the stalling, rough idle, sluggish response, completely disappeared. Quick tip though, make sure you get the sensor from a reputable parts supplier. I initially tried to save some money with a cheaper aftermarket part, but it didn't work right. Ended up going with an OEM sensor and haven't had any issues since. Just keep in mind that while this fixed my car, it's always good to have a proper diagnosis done. These symptoms can sometimes be related to other fuel system components too. Let me know how it goes after you get it checked out!

Thanks so much for the extra details and that really helpful tip about the OEM parts! I was actually thinking about going the cheaper route, but you've convinced me it's worth spending a bit more to do it right the first time. Really appreciate you mentioning your experience with the aftermarket part, definitely saved me some headache there. The mileage similarity makes me even more confident this is probably the same issue. I'll schedule an appointment with a BMW specialist tomorrow and make sure they use OEM parts for the repair. It's such a relief knowing this might not be as expensive or complicated as I feared. I'll definitely update this thread once I get it sorted out. Thanks again for taking the time to share your experience, it's been super helpful!