BMW i3 Hybrid Problems: Starting Issues and Misfires

Hey there! I have some experience working on hybrids and I actually dealt with something very similar on my 2016 BMW i8. When I first noticed these symptoms, I was really worried it might be something major. Took it to my regular workshop, and after diagnosis, it turned out to be a loose connection in the wiring harness to the camshaft sensor. The mechanic found that the plug had worked itself loose over time, causing intermittent connection issues. Total repair was 95 Euro, mainly labor costs for tracking down the issue and securing the connection properly. The symptoms were exactly what you're describing, trouble starting, misfires, and that annoying power loss. Real pain when trying to merge onto highways! Before I can help more specifically, could you share: Are there any other warning lights on? When exactly do the misfires occur (cold start, warm engine)? Which error codes are you getting? My i8 taught me that with these hybrid BMWs, what seems major often turns out to be something relatively simple like a connection issue. Let me know those details and I can probably point you in a more specific direction.

Thanks for your detailed response! Just want to chime in with my latest experience, I had my last service done about 3 months ago at 44120 KM, and everything was perfect until last week. The check engine light started flashing during acceleration, especially when the engine's warm. The error codes I'm getting are P0340 and P0341, which definitely point toward that camshaft sensor. What's interesting is that your wiring harness issue sounds really similar to what I'm experiencing, the problems seem to get worse when the engine bay heats up. I was worried it might be something more serious with the hybrid system, but your experience gives me hope it might be a simpler fix. Did your mechanic mention how long it took to track down that loose connection? I'm trying to figure out if I should block out a whole day for this repair.

Hey again! Glad to help further with this. Yeah, those error codes (P0340 and P0341) definitely match what I experienced with my i8. When you mentioned the problems getting worse with heat, that's exactly what happened with mine too, it's like textbook wiring harness behavior. Just to add to my previous experience, the actual repair time wasn't too bad once they found the issue. My mechanic spent about 2-3 hours total, but most of that was diagnostic time. The actual fix was pretty quick. The tricky part was accessing the harness connection since these hybrid engines are packed pretty tight. One thing I learned from my experience, make sure they check all the connections around that area while they're in there. After my initial repair, I had a similar issue pop up six months later because they didn't check the neighboring connections that had also started to work loose. Better to have them do a thorough check of all nearby wiring while they're accessing that area. You mentioned your issues start when the engine's warm, that's super helpful info. In my case, that was the biggest clue that led to finding the loose connection rather than a completely failed sensor. Heat expansion was making the connection even worse. Let me know how it goes, I'm really curious if it turns out to be the same issue as mine!

Thanks so much for all this information! It's really helpful knowing your repair experience worked out to be a relatively simple fix. Your tip about checking all the connections makes total sense, definitely don't want to deal with this issue twice! I just called my mechanic and scheduled an appointment for tomorrow morning. They said they should be able to diagnose and fix it within a few hours if it's indeed just a wiring issue. I'll make sure to ask them to check all the surrounding connections too, just like you suggested. It's such a relief to hear that when your i8 had these symptoms, it wasn't something catastrophic with the hybrid system. The way you described the heat-related issues matches my situation exactly, so I'm feeling pretty confident now that we're on the right track. I'll update the thread once I get it fixed. Thanks again for taking the time to share your experience, it's really helped me understand what I'm dealing with!