BMW M3 Trans Warning: Expert DIY Help Needed

Hey there. I had similar issues with my 2012 BMW M5 last year. The symptoms you're describing match what I experienced, warning lights, rough shifts, and limp mode. Initially thought it was just a sensor, but turned out the gearbox oil level was critically low, causing overheating and poor lubrication. Took it to my trusted mechanic who performed a full diagnostic. They found metal particles in the old transmission fluid, which indicated some internal wear. Required a complete transmission fluid flush, filter replacement, and they had to replace a worn clutch pack. It was a serious issue that could've led to total transmission failure if left unchecked. My advice: make sure they check the transmission fluid level and condition first. Ask them to show you the old fluid when they drain it, if it's dark or has metal particles, you'll need more than just a fluid change. Also, request a detailed diagnostic report before they start any major work. Don't wait on this one, these symptoms usually don't improve on their own.

Thanks for sharing your experience! That sounds exactly like what I'm dealing with, really helpful to know about the fluid level being the culprit in your case. Just curious, do you remember roughly how much you ended up paying for everything? And has your transmission been running smoothly since the repair, or have you noticed any other issues pop up? Really want to get an idea of what I might be looking at cost-wise and if I should prepare for any potential follow-up problems.

Hey again! Just wanted to follow up since I actually just got everything sorted with my M5. You'll be relieved to know that it was definitely the transmission temp sensor that was acting up, just like I suspected might be the case with yours. Got it fixed last week, they found the sensor was faulty and the gearbox oil level was running way too low. Total bill came to 365 € for everything. The best part? My transmission's running like a dream now, smooth shifts, no warning lights, and the car feels fantastic. Honestly wish I'd gotten it sorted sooner! Haven't had a single problem since the repair, and my mechanic reckons everything else in there looks solid. Definitely get yours checked out asap, these kinds of issues can spiral if you leave them too long. But based on what you're describing, sounds like you might be dealing with something similar to what I had. Just make sure they do a proper diagnostic before diving in. And like I mentioned before, get them to check that fluid level and condition, that's usually a good starting point. Hope this helps give you a better idea of what you might be looking at! Let me know how it goes.

Thanks everyone for the input. Just wanted to update you all on what happened with my M3. Finally got the car checked out yesterday and you guys were spot on! Went to this new mechanic who turned out to be fantastic. Really thorough guy who took the time to explain everything. Similar to what happened with your M5, my transmission fluid was super low and dirty. They found a small leak that had been slowly draining the fluid, which explained all those grinding noises and warning lights. The total damage came to about €450, not nearly as bad as I was expecting. They did a complete fluid flush, replaced the filter, fixed the leak, and checked all the sensors. Way better than my last mechanic who wanted to rebuild the whole transmission! Took it for a drive today and what a difference! Shifts are butter smooth now, no more warning lights, and the car feels like new. Honestly feel a bit silly for putting it off for so long. Really appreciate all the advice, saved me from potentially making the problem much worse (and more expensive)!