BMW 7 Series Trans Failure: Symptoms and Solutions

I had nearly identical issues with my 2015 BMW 5 series last year. The symptoms you're describing match what I experienced, rough shifting, warning lights, and limp mode activation. Initially thought it was major transmission damage, but turned out the transmission control module's wiring harness had deteriorated, causing faulty connections. The mechanic found that the connector pins were corroded and some wires were damaged. The grinding sound was actually the transmission getting confused signals from the bad connections, causing it to shift incorrectly. They replaced the wiring harness and cleaned all connection points. This wasn't a serious mechanical issue, but it definitely mimicked major transmission problems. After the repair, everything went back to normal, smooth shifting, no warning lights, and proper gear changes. Based on your description, I'd recommend having the electrical connections and wiring checked before assuming it's a mechanical transmission problem. Make sure whoever looks at it is familiar with BMW transmission control systems.

Thanks for sharing your experience with the transmission issue. That's really helpful to know it might be related to the wiring harness rather than a complete transmission failure. Can't help but wonder, how much did the repair end up costing you? Also, has everything been running smoothly since the fix, or have you noticed any other quirks pop up? Hoping to get an idea of what I might be looking at cost-wise and whether this is likely a permanent solution.

Hey there! Just wanted to follow up on your questions. After I had the wiring checked, they actually found it was the radiator oil pressure sensor that was acting up, not the wiring harness as initially suspected. The repair was pretty straightforward and only cost me 95 € to fix a faulty cable connection to the sensor. Since getting it sorted out, my 2015 BMW 5 series has been running like a dream! No more transmission problems, warning lights, or weird shifting issues. It's been about a year now, and I haven't had a single problem with the transmission. Looking back, I was really worried it would be something major, but it turned out to be a relatively simple and affordable fix. If your symptoms are similar to what I experienced, you might be looking at something equally straightforward. Just make sure you get a mechanic who really knows BMWs, it made all the difference in getting the right diagnosis. Let me know how it goes!

Just got back from the mechanic and wanted to update you all! You were spot on about finding someone who knows BMWs. The guy I went to this time actually specializes in German cars, and what a difference that made. He immediately knew what to check and found that my issue was similar but a bit different. Turns out the transmission fluid cooler was leaking, causing low fluid pressure and those scary warning lights. They had to replace the cooler and flush the transmission fluid. The whole thing cost around 800 bucks, more than your repair but way less than I feared! The grinding noise completely disappeared, and the transmission's shifting smoothly again. Really grateful for your advice about getting it checked before assuming the worst. The car's been running perfectly for the past week, no warning lights, no weird noises, nothing. Such a relief it wasn't a complete transmission failure! Thanks again for helping me avoid a panic-driven expensive repair at my old mechanic's place.