BMW 5-Series Alternator Woes: Starting & Power Issues

Hey there! I had very similar symptoms with my 2011 BMW 3 Series diesel last winter. Your description matches exactly what I experienced, weak engine performance, dimming lights, and multiple warning lights. Initially thought it was the alternator too, but when I took it to the garage, they diagnosed a defective generator (alternator unit). The generator wasn't providing enough power to charge the battery properly, which caused all those cascading issues. It was quite a serious problem that needed immediate attention, as it could've left me stranded anywhere. In my case, they had to replace the entire generator unit and reset the electrical system. The battery was also damaged from the constant draining and recharging cycles, so that needed replacement too. My car was at the garage for two days, but it's been running perfectly since then. The investment was worth it considering the potential damage it could've caused to other electrical components. I'd strongly suggest getting it checked soon, these symptoms typically don't improve on their own.

Thanks a lot for sharing your experience! It's really helpful to hear from someone who went through the same thing. Sounds exactly like what I'm dealing with. If you don't mind me asking, do you remember roughly how much you ended up paying for the whole repair? Also, has everything been running smoothly since the fix, or have you noticed any other electrical issues popping up? Just want to get an idea of what I might be looking at cost-wise and if I should expect any follow-up problems.

Hey again! Happy to help out with those details. I actually just got this fixed about two months ago, and I can tell you it cost me exactly 960 € for the generator replacement. Honestly, while it wasn't cheap, it was totally worth it because my car's running like a dream now. The electrical system is working perfectly, no more dimming lights, no warning signals, and the battery's holding charge just like it should. Since getting the generator fixed, I haven't had a single electrical issue pop up. Starting is smooth, the engine's got its power back, and all those annoying warning lights have stayed off. It's actually quite amazing how many problems one faulty generator can cause! I'd say go ahead and get it sorted soon, the peace of mind is worth every penny, and you definitely don't want to risk getting stranded somewhere. Plus, leaving it too long might end up damaging other components, which could make it even more expensive in the long run. Remember to get them to check the battery too while they're at it. Sometimes a faulty generator can damage it, but in my case, my battery was still good enough to keep.

Thanks so much for all this detailed info! Actually, I just got back from the mechanic today, and you won't believe it, it was exactly what you described. My generator was shot, and they had to replace it. Ended up costing me a bit more than what you paid because my battery was completely fried too. The whole experience wasn't as bad as I feared though. The mechanic I found was really honest and showed me all the worn-out parts. They got everything fixed in about a day and a half. Took it for a test drive earlier, and wow, what a difference! The car feels like new again, no more sluggish starts, all lights are bright and steady, and the engine's got its punch back. Really glad I didn't wait any longer to get it checked out. Thanks again for pushing me to get it looked at quickly, you were absolutely right about not letting it drag on. Here's hoping both our BMWs stay running smoothly now!