BMW 1 Series Rough Idle and Stalling, FPR Issue?

Hi there! I have some experience working on cars and went through something very similar with my 2017 BMW 3 Series. When my fuel filter was replaced, I had almost identical symptoms, rough idle, stalling, and poor performance. The check engine light also came on. Turned out the mechanic needed to properly reset the engine control module after the fuel filter change. The system wasn't reading the new filter correctly. Took it to my regular workshop, they hooked it up to their diagnostic computer, cleared the error codes, and did a proper reset procedure. Total bill was 45 Euro and fixed the issue completely. Before I can give more specific advice, could you share: How many miles/kilometers on your car? Was any recent work done on the fuel system? Are you getting any specific error codes? I've worked on several BMWs and these details would help pinpoint whether you're facing the same issue I had.

Thanks for the detailed response! Just to add some context, I'm at 120,126 KM and had my last service about 2 months ago. Actually, no recent work was done on the fuel system. The symptoms just started showing up suddenly last week. I used an OBD scanner and got P0171 code which points to a lean fuel mixture. Still really hoping it's just the fuel pressure regulator and not something more serious. The car has been well maintained since I got it new, so this is pretty frustrating. Anyone else had similar codes with these symptoms? Would love to hear more experiences before I take it in.

Hey again! Thanks for providing those extra details. You know what, when I read about your P0171 code, it actually sounds different from what I experienced with my BMW 3. I initially thought it was similar to my fuel filter situation, but your lean fuel mixture code makes me think differently now. Looking back at my experience with BMWs, when I had a failing fuel pressure regulator, it actually threw a different code. In my case, what first looked like a fuel pressure regulator issue turned out to be a vacuum leak from a cracked intake boot. The symptoms were almost identical to what you're describing, rough idle, stalling, poor performance, but the repair was much simpler and cheaper than replacing the regulator. Have you noticed any hissing sounds from the engine bay? With my car, I could actually hear the air leaking when I listened carefully at idle. My mechanic did a smoke test and found the leak pretty quickly. The fix was just replacing the intake boot, which cost way less than a fuel pressure regulator. I'd suggest getting a smoke test done before jumping to conclusions about the regulator. These BMWs are pretty sensitive to vacuum leaks, and the P0171 code is a classic symptom. Let us know what you find out, I'm really curious if your issue turns out to be similar to what I experienced.

Thanks everyone for the helpful insights! You know what, after reading about the vacuum leak possibility, I'm starting to think that might actually be what's going on. Now that you mention it, I do hear a faint hissing noise when the engine's idling, something I hadn't paid attention to before. I've booked an appointment with my mechanic for tomorrow morning and specifically asked them to do a smoke test first. It would be such a relief if it turns out to be just the intake boot rather than the fuel pressure regulator. I'll definitely update this thread once I find out what's actually causing the problem. Really appreciate all the BMW-specific knowledge here, having real experiences to compare with definitely helps narrow down the possibilities. Fingers crossed it's a simple fix like yours was!