BMW X4's Multiple Electrical Issues Need Expert Diagnosis

I dealt with nearly identical issues on my 2011 BMW X3 last year. After multiple warning lights and hard starts, it turned out to be a failing auxiliary battery plus some corroded terminals on the main battery. The start-stop system was the first to act up, which is typically a tell-tale sign. The aux battery handles a lot of the electronic systems while the main battery manages starting. When the aux battery starts failing, it puts extra strain on the main battery, leading to those starting issues you're describing. In my case, the fix involved replacing both batteries and cleaning the connections. It wasn't a hugely complex repair, but it needed proper diagnostic equipment to reset all the systems afterward. The car has been running perfectly since then with no electrical gremlins. Given the age and mileage of your X4, this sounds very similar to what I experienced. I'd recommend going to either a dealer or a reputable BMW specialist who has the right diagnostic tools. It's not the most serious issue, but it needs proper attention to prevent damage to other electrical components.

Thanks for sharing your experience! That's super helpful since it sounds exactly like what I'm dealing with. Quick question, do you remember roughly how much you ended up paying for the whole fix? Also, has everything stayed working properly since the repair, or have you noticed any other electrical quirks pop up?

Hey there! Just wanted to follow up since you asked about the costs and long-term results. After taking my X3 to a proper mechanic, it cost me 290 € to fix the auxiliary battery issue, which wasn't too bad considering how much hassle it was causing. I'm really happy to report that since getting it fixed, all those annoying electrical problems completely disappeared! The start-stop system works perfectly now, no more warning lights on the dash, and the car starts up like a champ every single time. It's been such a relief not having to worry about whether the car will start or what new error message might pop up. It was definitely worth getting it sorted by a professional who knew what they were doing. Having the right diagnostic equipment made all the difference, they were able to properly reset everything after installing the new battery. I'd say if you're experiencing similar issues, don't wait too long to get it fixed. These electrical problems tend to only get worse if you leave them. Best part is I haven't had a single electrical issue since the repair. The car runs just like it should, which honestly makes me wish I'd done it sooner!

Thanks so much for the detailed info! I actually just got back from a certified mechanic who confirmed it was indeed the auxiliary battery. Pretty wild how accurate your diagnosis was! The total came to about 320 € for the new battery, labor, and system reset. A bit more than I wanted to spend, but already seeing a huge difference. No more dashboard light show, and the start-stop is working perfectly again. Such a relief! The mechanic I found was great, took the time to explain everything and showed me the old battery's condition. Made me feel much better about the whole thing after my previous bad experience. They even did a full electrical system check to make sure there weren't any other issues lurking. Really appreciate everyone's help here. It's such a weight off my mind having this sorted properly. Time to actually enjoy driving my X4 again without wondering if it'll start each morning!