BMW i8 Cold Start Mystery: Hybrid Won't Wake Up

Hey there, i8 owner! I had a similar issue with my 2016 BMW i3. The symptoms you're describing sound exactly like what I experienced last month. Initially thought it was the engine control unit, but when I took it to the garage, they found severely corroded battery terminals and loose cable connections. The mechanic showed me how the corrosion was preventing proper current flow, which explained the inconsistent starts and complete failures, especially during cold starts. They had to clean the terminals thoroughly, replace the cables, and ensure proper connection. It wasn't a major repair, but definitely not something to ignore as it could lead to more serious electrical system issues. My advice would be to have someone check your battery connections first before diving into more complex engine control diagnostics. The hybrid system relies heavily on proper electrical connections, and even minor connection issues can cause the symptoms you're describing.

Thanks for sharing your experience! That's really helpful, seems like we had pretty similar issues. My regular starts are fine now after getting it fixed, but during those super cold mornings, it occasionally acts up a bit. By the way, do you remember roughly how much you paid for the repair? Also, has everything been running smoothly since they fixed it, or have you noticed any other quirks? Just want to make sure I'm not missing anything important with mine.

Hey again! Glad to help out a fellow BMW owner! Yes, I remember exactly what I paid, it was 155 € to fix those pesky battery cable connections. And I've got great news to share, since getting that repair done, my engine control malfunction completely disappeared! The car's been running like a dream, even during those chilly mornings. Honestly, it was such a relief when it turned out to be just the cable connections rather than something more serious with the engine control unit. My i3 starts up perfectly now, no matter what the temperature is. It's amazing how something seemingly minor like corroded battery terminals can cause such annoying problems with these high-tech hybrids. Since you mentioned cold morning issues, might be worth having them double-check the connections again just to be on the safe side. But from my experience, once they get those electrical connections sorted properly, you shouldn't have any more problems. The whole hybrid system really depends on having solid electrical connections.

Just wanted to update everyone about my i8 situation. Finally took it to a different mechanic yesterday, and guess what? It was indeed a battery connection issue! The new mechanic was fantastic, really knew his stuff about hybrid systems. He found heavy corrosion on the terminals and some loose connections, just like mentioned. The repair cost me a bit more than's, around 200 bucks, but included a thorough cleaning and replacement of some worn-out cables. They also checked the entire electrical system while they were at it. Started the car this morning in the cold, and it fired up perfectly! No more weird hesitation or failed starts. Looking back, I probably wasted time and money at that first mechanic who couldn't figure it out. Really appreciate everyone's input here, especially's experience, it pointed me in the right direction. Sometimes the simplest solutions are the best ones. Thanks again for all the help!