BMW 3 Hybrid Cold Start Issues, Rough Idle & High Fuel Use

Hey there! I have some experience working on cars, and I actually faced a similar issue with my 2020 BMW 5 Series Hybrid (had to trade it in for a BMW 7 later). The symptoms you're describing sound exactly like what I dealt with. Mine turned out to be a faulty injector. I took it to my regular workshop, and they diagnosed it after running some tests. The whole repair, including parts and labor, set me back about 515 Euro. They had to replace one injection valve that was completely shot. The fix made a huge difference, no more rough starts, and fuel consumption went back to normal. However, before jumping to conclusions, could you share: Any warning lights on the dash? How many miles/kilometers on your car? When did you first notice these symptoms? This would help me understand if you're dealing with the same problem I had.

Thanks for sharing your experience! I've got 116122 KM on the clock, and the symptoms started just after my latest service. No warning lights showing up on the dash yet, which is kind of weird considering the rough starts. The fuel consumption increase happened gradually over the past couple weeks, and it's most noticeable when the engine's cold. Your injector issue definitely sounds similar to what I'm experiencing. Did your car also have that slight shudder during cold starts before you got it fixed?

Hey again! Yes, absolutely, that slight shudder during cold starts was exactly what I experienced with my BMW 5 Series before getting it fixed. It's quite interesting that your symptoms started after the service, makes me wonder if something got disturbed during the maintenance. In my case, that shudder was one of the main red flags, especially in the first 30 seconds or so after starting. The lack of warning lights on your dash is actually pretty common with these issues, mine didn't show any either until much later. The gradual increase in fuel consumption matches my experience too. One thing I forgot to mention in my first reply, before I got the injector replaced, I tried running some fuel system cleaner through it, thinking it might just be carbon buildup. Didn't help at all in my case, but might be worth a shot before spending big money on repairs. Have you noticed any black smoke from the exhaust during those cold starts? That was another symptom I had that confirmed it was injection-related. Also, does your engine seem to run smoother after it warms up? With your mileage being similar to what mine was when I had the problem, I'm even more convinced we're looking at the same issue.

Thanks for all that additional info! Actually, yes, I have noticed a bit of black smoke during cold starts, though it's not super obvious. And you're spot on about the engine running better once it's warmed up, after about 5-10 minutes of driving, it smooths out considerably. I think I'll take your advice and try the fuel system cleaner first, even though it didn't work for you. At least it's a cheaper option to start with. But honestly, given how similar our symptoms are, I'm pretty much expecting to end up replacing that injector. Good to know about the cost too, helps me budget for the worst-case scenario. I'll get it into the workshop next week and let you know what they find. Really appreciate you taking the time to share your experience, it's given me a much better idea of what I'm dealing with!