BMW M4 FlexRay Nightmare: Total Electrical System Failure

Hey! I have some experience working on cars, and I actually faced a similar issue with my 2018 BMW M3. The symptoms were nearly identical, electrical gremlins all over the place. After some headaches, turned out it was just a faulty wiring connection near the main control module. My trusted workshop found that one of the cable connectors was corroded and making poor contact. They had to clean the connection points and replace the damaged cable section. Total bill came to 95 Euro, which wasn't too bad considering how much I was worried it could be. Before I can help more specifically with your case, could you share: Are all electrical issues happening at the same time or intermittently? Have you noticed any warning lights on the dashboard? Did this start suddenly or gradually get worse? This could help pinpoint if you're dealing with the same connection issue I had, or if it's something different in your M4.

Thanks for sharing your experience! I've got 167267 KM on the clock, and these issues started popping up about two weeks after my latest service. To answer your questions, everything's happening out of nowhere, not all at once. The warning lights are pretty inconsistent, they come and go. It definitely got worse over time, started with just the audio system acting weird, then spread to other systems. Your wiring connection issue sounds promising, might be worth checking that first before diving deeper into the FlexRay system. Did your M3 also have these unusual, intermittent failures before you got it fixed? Just trying to see if the symptoms match up completely before I head to the workshop.

Hey there again! Yeah, reading your latest response definitely rings some bells with what I experienced in my M3. Those unusual, intermittent failures were exactly what I was dealing with too, it was super frustrating! Mine also started with the audio going wonky before everything else started acting up. The similarity in symptoms is actually making me more confident it's likely the same wiring issue I had. My car was showing the exact same pattern, unusual warning lights popping up and disappearing, systems failing intermittently rather than all at once. The fact that yours started after a service is interesting too, sometimes when work is done, connectors don't get seated quite right, or something gets knocked loose. I remember being really worried about the FlexRay system too, but honestly, seeing how your symptoms are progressing exactly like mine did, I'd put money on it being that wiring connection issue. When my mechanic found those corroded connections, they showed me how even slight movement could cause all those unusual failures, it was basically creating an intermittent connection that was messing with everything. Quick tip, before you take it in, try listening for any slight clicking sounds from the main control module area when these issues occur. That was actually something I noticed in mine, though I didn't realize its significance at the time. Let me know what you find out, really curious if it turns out to be the same issue!

Thanks so much for all that detailed info! Really helpful to hear your experience matched mine so closely. I just checked and I actually can hear that clicking sound you mentioned, definitely going to get those connections looked at first. You've saved me from going down the FlexRay rabbit hole and potentially wasting time and money. I've already called my workshop and booked it in for tomorrow morning. Made sure to mention the wiring connection possibility and described everything we discussed. They seemed to think it was a solid lead to start with, especially given how similar it is to what happened with your M3. Really appreciate you taking the time to walk me through your experience, looks like I might be sorting this out way cheaper than I initially feared! I'll update you once I get the diagnosis back from the workshop. Fingers crossed it's just those pesky connections like in your case!

I have the same issue but my car is a 330e 2017 Can any one tell me what connections I need to check and were they are located

Start by checking the battery terminals and ground connections for any signs of corrosion or looseness, as these are common culprits for electrical issues. Ensure they are clean and securely fastened. If the problem persists, it might be best to consult a professional mechanic, as electrical issues can be complex and safety-critical. Let me know how it goes or if you have more questions!