Hi everyone Im new to the board and Im having a weird issue even my buddy who use to own a bmw shop is boggled by. So I have a 2008 550i m sport and when I have it in sport mode and put it in manual when say Im in 4th gear and began to slow I downshift with the paddle or the stick down to 3rd then 2nd sometimes it works but lately it will down shift for a split second then send the transmission upshifting sometimes all the way up to 5th gear. Something else I noticed tho is that I can override the issue with staying on the accelorator this rules out an electical issue in my mind. So if I brake with my left and with my right foot slightly on the accelerator it will downshift. This is obviously not a good resolution but it was a work around I discovered while I was just trying to trouble shoot the system. It will also down shift manually almost to the point of redline if I am still on the accelerator but as soon as I try downshifting while not on throttle and slowing down it will upshift after I down shift. Any guesses or help would be much appreciated.

Car has 64k miles. I was going to do a transmission drain and refill soon. I bought the car with 50k miles used from a dealer car seemed unabused and is super clean. I drive the car pretty relaxed on a commuting day to day basis but on the weekends I tend to drive it pretty aggresive. I have a hand held scanner and the car is not displaying any fault codes or errors. Nothing else seems to be wrong no shifting issues or driveability issuses.

Also just an addition I believe its a SAT transmission.

Ok Ill run the Vin here shortly, my buddy gave me this scanner iCarsoft Multi-system Scanner i910 for BMW/Mini_BMW/Mini Scan Tools

he sold his other scanners to his partner when they sold the shop. I just did a run to get lunch and tried the hold the paddle when I down shifted when I started having the problem again and that seems to be another work around for the issue.

So looked up my Vin and I do have the SAT Transmission. Its possible that the trans fluid is low, but I have zero leaks on my car *knock on wood* I know these things are known for having their oil leak issues once they start getting either old with age or mileage. But when I did my last oil change I removed the under belly cover and no oil was present but that was 3k miles ago so I can check again when I do my differential swap in a couple weeks. Something that tells me that its not electrical is that I have found a work around and now when I down shift I hold the paddle down until Im almost ready to down shift again and it stays in the gear. I Have only seen the issue again when I dont hold the paddle down now and its very intermittent.