BMW 3 Series Won't Start: Weak Crank & Flickering Lights

Hey there! I have some experience working on cars and went through something very similar with my '02 BMW 5 Series last year. What you're describing sounds exactly like what happened to mine. Turned out that a previous repair shop had improperly installed a new alternator, which caused damage to the battery and electrical system. Since it was their fault, they fixed everything free of charge, replaced both the alternator and battery, and rechecked all connections. Before jumping to conclusions though, could you share: Current mileage? What's the exact error code you're getting? When was the last time you had any electrical work done? This could help narrow down whether you're facing the same issue I had. Might save you some time and money figuring it out!

Hi! Thanks for sharing your experience. My BMW has 40992 KM on the clock and just had its service last month. I'm getting error code P0615 which points to the starter circuit. Haven't had any electrical work done recently except for routine maintenance. Really appreciate the detailed response about your alternator issue, it's giving me a good starting point to investigate. Do you remember roughly how much the parts cost when they fixed yours? Might help me budget for what's coming.

Oh hey again! Yeah, seeing that error code P0615 definitely brings back memories of my BMW troubles. In my case, when the shop fixed my alternator and battery issue, the parts alone were around 800 € for a genuine BMW alternator and about 200 € for a high-quality battery. Labor was extra, but since they messed up the initial install, they covered everything. But with your error code specifically pointing to the starter circuit, and given you've had recent service work, I'm thinking your issue might be different from what I experienced. Have you noticed any other symptoms besides the weak start and flickering lights? In my case, I remember the battery warning light would come on intermittently while driving too. The good news is that if it's just the starter, it should be cheaper than what I had to deal with. My mechanic mentioned that a starter replacement typically runs between 400-600 € including labor. Just make sure whoever works on it uses genuine BMW parts, I learned that lesson the hard way with my alternator situation! Let me know what you find out. I'm curious if this turns out to be simpler than my alternator nightmare!

Thanks so much for all that detailed info about the costs! Really helpful to know what I might be looking at expense-wise. Actually, now that you mention it, I haven't seen any battery warning lights while driving, which makes me feel a bit better about ruling out alternator issues. You're probably right about it being different from your situation, especially with that P0615 code specifically pointing to the starter circuit. I think I'll take it to my mechanic tomorrow and mention everything we've discussed. At least 400-600 € sounds way better than what you had to deal with! And thanks for the tip about genuine BMW parts, definitely don't want to cheap out and end up paying more in the long run. I'll update the thread once I find out what's actually wrong with it. Really appreciate you taking the time to share your experience!