BMW Won't Start in Park: Transmission Lock Mystery

I had nearly identical symptoms with my 2006 BMW 5 Series diesel (E60) last year. Initially thought it was just the transmission, but turned out the car's control unit was defective. The control unit wasn't properly communicating with the transmission module, causing those weird start-up issues and rough shifts. Got it fixed at a shop specializing in BMW transmissions. They had to replace the control unit and reprogram the transmission module. It was a serious job that took about 4 days to complete due to parts availability and programming time. The rough shifting and starting problems completely disappeared after the repair. If you're experiencing similar symptoms, I'd strongly suggest getting the control unit checked first before assuming it's a mechanical transmission issue. Make sure to find a shop with proper diagnostic equipment for BMW vehicles.

Hey! I went through something really similar with mine! That control unit fix sounds exactly like what happened with my car. Just wondering, do you remember roughly how much you ended up paying for the whole repair? And has everything been running smoothly since then, or have you had any other issues pop up? Really trying to figure out if I should expect any follow-up problems down the line.

Hey there! Actually, great timing on your question, I just wanted to update that everything's been running perfectly since I got it fixed. The total bill came to 1000 € for the control unit replacement and reprogramming work. I know it wasn't cheap, but honestly, it was worth every penny. The transmission's working like new now, no more trouble starting in park, and those annoying rough shifts are completely gone. Since the repair, I haven't had a single issue, it's been about a year now. The car shifts smoothly, starts normally every time, and that pesky check engine light hasn't come back on. My mechanic did a really thorough job with the control unit replacement, and I think that's why I haven't seen any follow-up problems. From what I've learned, once you get the control unit properly sorted out, these transmissions are pretty reliable. Just make sure you keep up with regular maintenance, and you should be good to go. Sounds like you're dealing with the exact same thing I did, so hopefully this gives you some peace of mind about the repair!

Thanks for all that info! I bit the bullet and took my car to a mechanic yesterday. Turns out you were spot on, it was the control unit. They quoted me slightly higher at 1200 €, but I went ahead with the repair since the symptoms matched exactly what you described. The mechanic I found was actually great, really knew his stuff about BMWs. He explained everything clearly and even showed me the faulty unit. Took them three days to get it done, but the car's running like a dream now! Starts perfectly every time, no more rough shifting, and that annoying check engine light is finally off. Honestly, I'm just relieved it wasn't a full transmission replacement like I initially feared. The whole experience wasn't nearly as stressful as I thought it would be. Thanks again for sharing your experience, it really helped me make the decision to get it fixed properly instead of trying cheaper alternatives that probably wouldn't have solved the issue.