BMW 1 Diesel: Air Intake Issues & Performance Problems

Hey there! I've got some experience with BMWs, I drive a 2019 BMW 2 Series diesel myself (previously had a 3 Series too). Had almost identical symptoms last year, that hissing sound really had me worried! Turned out it was just a cracked intake hose. My trusted mechanic spotted it pretty quickly during inspection, there was a split in the rubber hose that was causing air to leak. Got it replaced and boom, all those issues disappeared instantly. The whole thing cost me around 100 bucks for parts and labor. Money well spent since my fuel consumption went back to normal and the engine's been running smooth since then. Before I can help more specifically though, which engine variant do you have in your 1 Series? And have you noticed if the symptoms get worse when you accelerate hard? This info would help compare our situations better. Quick tip: Don't wait too long on this one, running with an intake leak can cause more problems down the line.

Thanks for sharing your experience! My car's actually at 192925 KM, and I just started noticing these issues a couple weeks after my latest service. I've got the B47 engine variant, and yeah, the symptoms definitely get worse during hard acceleration. The hissing sound you mentioned is exactly what I'm hearing too. Interesting that a simple cracked hose caused all those problems in your case. That's somewhat reassuring, as I was worried it might be something more serious. Did your engine light stay on continuously when you had this issue? Mine seems to come and go out of nowhere, which is pretty frustrating. Been trying to limit my driving until I can get this sorted out. Think I'll get it checked out this week, don't want to risk any bigger problems developing.

Hey again! Yes, I remember exactly what you're going through, my engine light was doing the same unusual on-off dance when I had that cracked hose on my 2019 2 Series. Super annoying, right? Actually, when you mentioned the mileage and that it started after a service, it reminded me that my issue popped up after a routine maintenance too. Sometimes these hoses can get damaged during other work if they're not handled carefully. With my B47 engine (same as yours), the hissing was most noticeable when I'd push it from 2000 to 3000 RPM. The unusual engine light thing turned out to be because the engine computer was detecting inconsistent air-fuel ratios, sometimes within acceptable ranges, sometimes not. I know you're planning to get it checked this week, that's smart. When my mechanic fixed mine, he actually showed me the crack in the old hose. It was pretty subtle, but what a difference that tiny split made to performance! Just make sure they do a proper pressure test on the entire intake system. There might be multiple spots leaking. Still one of the best fixes I've done, car's been running like new since then. Let me know how it goes with yours!

Thanks so much for all the detailed info! Yeah, my symptoms match yours exactly, especially that RPM range where the hissing gets louder. Actually feeling more optimistic now that it might just be a hose issue rather than something major. Called my mechanic and got an appointment for tomorrow morning. Made sure to mention the pressure test you recommended, he said that's exactly what they'll check first. He seemed to think it's likely an intake leak too, especially given the symptoms and the timing after the service. Really appreciate you taking the time to share your experience in such detail. It's been super helpful knowing what to expect and what to ask the mechanic to check. Will definitely update once I get it sorted out, might help someone else with similar issues down the line! Let's hope it's just a simple hose replacement like in your case. Your repair cost sounds way better than some of the scary numbers I was imagining! Thanks again for all the help!