BMW X6 Battery Woes Causing Multiple System Failures

Hey there! Had the same problems with my 2010 BMW X5 35i last summer. Started with unusual warning lights, then the start-stop feature went crazy, and eventually, the car wouldn't start properly. Turned out it was indeed the auxiliary battery failing. Took it to a certified shop and they diagnosed both batteries (main and auxiliary). The auxiliary battery was completely dead and wasn't holding charge anymore. They had to replace it and reprogram the battery management system. It wasn't a complicated fix, but it needed proper diagnostic equipment to reset everything correctly. Since the replacement, all electrical issues disappeared completely. The car starts perfectly now, and all systems work as they should. Just make sure whoever works on it knows BMW electrical systems, it's not just a simple battery swap like in regular cars. My advice would be to get it checked soon before it leaves you stranded somewhere. I learned the hard way that these electrical issues don't fix themselves.

Thanks for sharing your experience! This sounds exactly like what I'm dealing with. It's really helpful to know it worked out with just a battery replacement and reprogramming. Could you remember roughly how much the whole job cost you? Also, has everything been running smoothly since the repair, or have you noticed any other electrical quirks pop up? I'm definitely planning to get it sorted soon, don't fancy being stuck somewhere with a dead car!

Hey again! Happy to help update you on the cost and outcome! The total bill came to 290 € for everything, that covered the new auxiliary battery, programming, and labor. I'd say it was money well spent considering the headaches it was causing before. Since getting it fixed last summer, I'm pleased to say everything's been running like clockwork. No more warning lights, the start-stop system works perfectly, and most importantly, no more of those nerve-wracking moments wondering if the car would start! It's amazing how one failing component can cause so many weird issues in these modern BMWs. The mechanic mentioned these auxiliary batteries typically last about 7-8 years, so the timing made sense for my X5. Given your X6's age, it sounds like you're in the same boat. Just get a proper BMW specialist to handle it, they'll have the right diagnostic tools to reset everything correctly. Trust me, you'll feel the difference immediately once it's sorted. Let me know how it goes when you get it fixed!

Thanks so much for all the detailed info! I actually took your advice and got it sorted yesterday. You won't believe how similar my experience was! The mechanic confirmed it was the auxiliary battery, just like you said. My bill came in a bit higher at 350 € because they found some corroded terminals they had to clean up, but honestly, it was worth every penny. The car's running like a dream now. No more warning lights, and that annoying start-stop issue is completely gone. Had quite a laugh at the shop actually, while they were working on it, another BMW pulled in with almost identical symptoms! Guess these auxiliary batteries really are a common issue. The mechanic did mention they're seeing more and more of these cases lately. Really grateful for your help, saved me from worrying too much and pointed me in the right direction. Car's starting up perfectly now, and all those electrical gremlins seem to have disappeared. Feels good to have a reliable car again!