BMW i8 Hybrid Issues: Stalling and Power Loss Mystery

Hey there! I have some experience working on hybrids and I can relate to your issue. I had similar symptoms with my 2016 BMW i3 last year. The problems you're describing sound exactly like what I went through, unstable idle, power issues, everything. After some troubleshooting, it turned out to be a defective pressure sensor, just as you suspect. I took it to a workshop specializing in hybrids, and they confirmed the diagnosis. The repair cost me around 240 Euro, but it fixed all those issues completely. Haven't had any problems since then. Can you tell me if you've noticed any particular pattern when these symptoms occur? Like during cold starts or after driving for a while? Also, have you scanned for error codes? This info would help me give you more specific advice based on my experience. BTW, both the i3 and i8 share similar sensor systems, so you might be dealing with the same thing I did.

Thanks for sharing your experience! My i8 is showing these symptoms mainly during cold starts, and they seem to get worse after about 15-20 minutes of driving. I've had the car since new, and it's been regularly serviced, last one was just about 2 months ago at 32832 KM. I haven't scanned for error codes yet, but I'm planning to get that done this week. The weird thing is that the problems started quite suddenly, like within a couple of days. It's good to know that fixing the pressure sensor solved similar issues for you, gives me hope it won't be something more serious! By the way, did your repair include any software updates? Just wondering if that might be part of the solution too.

Hey again! Glad you found my previous reply helpful. Based on what you're describing about the cold starts and symptoms getting worse after driving, it sounds even more similar to what I experienced with my car. When my issues started, they also came on pretty suddenly, literally went from perfect running to problematic in about 3 days. And yes, actually, there was a software update involved in my repair! The technician explained that updating the engine management software was necessary after replacing the pressure sensor to ensure everything worked properly together. Since you mentioned your car's been regularly serviced, that's actually good news, makes it less likely to be something more serious. My car had about 45000 KM when this happened, so we're in a similar ballpark maintenance-wise. Quick tip from my experience: when you get the error codes scanned, make sure they check both the engine and hybrid system codes. In my case, there were actually two related codes that helped pinpoint the exact issue. Let me know what the scan reveals, I'm really curious to see if it's the same problem I had. The symptoms match up so closely, I wouldn't be surprised if it is!

Thanks for that detailed follow-up! It's actually a huge relief to hear your BMW had such a similar pattern, especially the part about the sudden onset of problems and how the software update was part of the fix. I just got back from having those error codes scanned, and you won't believe it, they found both engine and hybrid system codes, just like you mentioned! The main code was P0193, which apparently points directly to the fuel rail pressure sensor. There was also a hybrid system code indicating some communication issues. I've already booked the car in at a specialist workshop for next week. They quoted me roughly the same price range you mentioned, including the software update. Really hoping this sorts everything out like it did for your i3! Thanks again for all your help, it's been super reassuring to talk to someone who's been through the same thing. I'll probably post an update once it's all fixed to help out anyone else who might run into similar issues with their i8 in the future.