BMW 5 Series Hybrid Problems: Rough Idle & Stalling

Hey there! I've got some experience with BMWs, as I own a 2015 BMW 3 Series Hybrid and previously had a 5 Series. What you're describing sounds similar to what I dealt with last month. I had comparable symptoms, rough idle, starting issues, and increased fuel consumption. Initially thought it was the fuel pump too, but it turned out to be a loose connection in the wiring harness that connects to the hybrid system's control unit. My mechanic found it during diagnostics, and it was causing all sorts of weird behaviors. The fix wasn't too complex, they had to reconnect and secure the cables properly, plus replace a damaged connector. Total bill came to 95 Euro, and they had it done in about 2 hours. Before I jump to conclusions though, could you share: Current mileage on your car? What specific error codes are you getting? Did these issues start suddenly or develop gradually? This info would help determine if you're dealing with the same problem I had.

Thanks for sharing your experience! My car has 148857 KM on the clock and had its last service about 3 months ago. What's interesting is that my issue started gradually over the past few weeks, it wasn't a sudden failure like yours. The main error code I'm getting is P0171 (system too lean), along with a hybrid system warning. I'm actually relieved to hear it might be something as simple as a wiring issue rather than a fuel pump problem. That repair cost sounds much better than what I was expecting to pay! Did you notice any battery-related warnings before fixing the wiring issue? Just wondering because I've seen some battery fluctuations on my dash display too.

Hey again! Yeah, actually I did notice battery fluctuations on my dash before getting the wiring fixed. The hybrid system is pretty sensitive to electrical irregularities. Given that you mentioned P0171 and the gradual onset, it does sound quite different from my situation though. With that mileage and the "system too lean" code, I'm starting to think it might be related to your fuel system after all, but possibly not the pump itself. After dealing with my wiring issue, I did some research and learned that these hybrid models can show similar symptoms when there's an issue with the fuel pressure regulator or fuel injectors. When my mechanic was working on my car, he mentioned that the 5 Series hybrids from around 2017 sometimes have issues with the fuel pressure regulator getting sticky over time. Might be worth having that checked specifically. The battery fluctuations could be the hybrid system trying to compensate for the irregular fuel delivery. I'd suggest getting a full diagnostic scan first, proper diagnosis saved me from unnecessarily replacing the fuel pump. Have you noticed if the issues get worse when the engine is warm or cold? That detail helped narrow down the cause in my case.

Thanks for that detailed follow-up! That's really interesting about the fuel pressure regulator, I hadn't considered that possibility. Now that you mention it, the issues definitely seem worse when the engine is warm, especially after driving for about 20 minutes or so. You've given me a much better direction to explore with my mechanic. I was so focused on the fuel pump that I hadn't considered the regulator or injectors. I'll definitely get that full diagnostic scan done first before replacing any parts. It's good to know these symptoms don't necessarily mean an expensive fuel pump replacement. I really appreciate you sharing your experience and knowledge about these hybrid BMWs. I'll schedule an appointment with my mechanic tomorrow and specifically ask them to check the fuel pressure regulator and injectors. Will let you know what they find if you're interested!