BMW i4 Electric Motor Issues: Jerking and Power Loss

Hey! I have some experience with EVs and had a similar issue with my BMW iX from 2022. I feel your pain! Had the exact same symptoms on mine, jerking and power reduction. Turned out I had gotten a third-party performance tune installed at a non-BMW shop that messed with the motor control unit. Took it to a certified BMW workshop, they reset the software and removed the faulty tune. Cost me around 180 Euro but solved the problem completely. Before I can give more specific advice, what year is your i4 and have you had any recent modifications or software updates done? This info would help me understand if we're dealing with the same issue. Hope this helps! Let me know if you need more details.

Thanks for sharing your experience! My i4 is completely stock without any modifications or third-party tunes. It's a 2020 model and just had its latest service completed. Currently sitting at 29608 KM on the odometer. Unlike your case, I haven't made any changes to the original software or hardware. That's what makes this issue more concerning for me. Did you notice any warning lights or specific error messages before your car started acting up? Also, how long did the diagnosis process take at the BMW workshop?

Hey again! Thanks for providing those details about your i4. You're right, our situations are a bit different since yours is stock. In my case, before the jerking started, I did see the yellow drivetrain warning light come on, but I initially ignored it (not smart, I know). The diagnosis at BMW took about 2 hours. They hooked up their diagnostic computer and found multiple error codes related to the motor control unit. Since your car is stock, I'm thinking it could be a faulty sensor or maybe even an issue with the high-voltage battery management system. These symptoms can show up even in properly maintained cars. On my iX, before the tuning incident, I had a similar power reduction issue that turned out to be just a bad connection in one of the motor sensors. Have you noticed any patterns when the jerking occurs? Like during acceleration or at specific speeds? This could help narrow down the cause. Also, does the power reduction happen immediately when you start the car or after driving for a while? I'd definitely recommend getting it checked at a BMW service center since EVs can be tricky to diagnose. Would love to hear what they find, might help other i4 owners too!

Thanks so much for the detailed response! Actually, yes, I should've mentioned this earlier. The jerking mostly happens during hard acceleration, and the power reduction seems to kick in after about 15-20 minutes of driving. The yellow drivetrain warning light you mentioned, I've got that too, it started flashing about a week ago. You've convinced me to take it to the BMW service center rather than trying to figure it out myself. The sensor issue you mentioned seems like it could be the culprit, especially since the symptoms are so similar. I'll book it in tomorrow and definitely let you know what they find. Really appreciate you taking the time to share your experience, it's helped me understand what I might be dealing with. Will update you once I get the diagnosis!