BMW 4 Series Transmission Failure: Symptoms and Solutions

Hey there! I have some experience working on BMWs. Actually went through something similar with my 2020 BMW 2 Series last year. Those transmission symptoms sound very familiar, had the same warning lights and rough shifting issues. Turned out it was just a faulty wiring connection to the transmission control module. The mechanic found a damaged cable harness that was causing intermittent connection problems. Got it fixed for around 95 Euro, mostly labor costs for diagnosing and replacing the connection. Before jumping to conclusions about the radiator oil pressure though, it would help to know: How many miles/kilometers are on your 4 Series? Did this start happening suddenly or gradually? Any other warning messages on the dash? Let me know these details and I might be able to help point you in the right direction based on my experience!

Thanks for the detailed response! My 4 Series has 5387 KM and just had its last service. The issue actually started quite suddenly, was driving normally one day and the next morning all these symptoms showed up at once. No other warning lights besides the transmission and check engine. Really appreciate you sharing your experience with the wiring harness issue. That's actually a relief to hear it might be something relatively simple like that rather than a major transmission problem. Hoping I get lucky like you did with a straightforward fix! Did your BMW display any specific error codes when you got it scanned?

Hey again! Thanks for those extra details about your 4 Series. You know what's interesting, my situation was super similar with the sudden onset of issues. When I had my 2 Series scanned, it showed error code P0700 (transmission control system malfunction) and P0715 (input/turbine speed sensor circuit). The fact that yours started suddenly just like mine, and with such low mileage too, makes me even more convinced it could be electrical rather than mechanical. When my wiring harness issue happened, I had around 6000 KM on the clock, so pretty close to your mileage. Quick tip though, get it checked soon! I initially kept driving mine in limp mode for a few days (bad idea, I know), which could've potentially caused more damage. With yours being even newer than mine was, it's definitely worth having a proper diagnostic done. The good news is that if it is just a wiring issue like mine was, it's typically covered under warranty. Let me know what you find out when you get it looked at. I'm really curious if it turns out to be the same problem. These newer BMWs can be pretty sensitive to electrical gremlins, but usually, they're not too serious when caught early.

Thanks so much for all this information, it's super helpful! Those error codes you mentioned are giving me hope that my issue might be similar to yours. I'll definitely get it checked out right away instead of risking any additional damage. You're right about not driving it too much in this condition. I've actually already called my BMW dealer and booked it in for tomorrow morning. Fingers crossed it's just a wiring issue like yours was! Really glad I posted here, you've saved me a lot of worry about potential major transmission problems. I'll definitely update once I know what's going on with it. Thanks again for sharing your experience and the warning about not driving it too long in limp mode!