BMW Z4 Multiple System Failures, ECU Investigation Needed

Hey there! I have some experience working on BMWs and had a very similar issue with my 2014 BMW 4 Series (also owned a 3 Series before). Those symptoms definitely sound familiar. My car was doing almost exactly the same, unusual system failures, infotainment going crazy, and weird error messages popping up everywhere. Turned out it was a faulty cable connection to the main control unit that was causing communication issues across the BUS system. The workshop diagnosed it and found some damaged wiring that was causing intermittent connection problems. Got it fixed by replacing the affected cables and connectors. Cost me around 155 Euro for the whole job, but it solved all those unusual glitches completely. Could you share more details about when these issues started and if you notice any pattern when they occur? Like does it happen more when it's cold or after driving for a while? This info would help confirm if you're dealing with the same problem.

Thanks for sharing your experience! My Z4 is at 116224 KM and just had its service last month. Those symptoms sound exactly like what I'm dealing with! The issues started popping up out of nowhere about two weeks ago, and interestingly, I notice it happens more frequently when the engine is warm, especially after driving for about 30 minutes. The weird part is that sometimes everything works perfectly fine for a day or two, then suddenly all these glitches start happening again. It's quite annoying when you're driving and the systems start acting up. Your cable connection theory makes a lot of sense, I'll definitely have my mechanic check the wiring and connectors. The price you mentioned for the fix sounds reasonable if it solves all these unusual issues. Did you experience any warning lights on the dashboard along with these problems? Just wondering if I should expect any other symptoms to show up.

Oh hey again! Yes, I remember those issues with my 4 Series perfectly. Actually, when you mention the problems occurring more after 30 minutes of driving, that's exactly what I experienced too. And yes, I did get warning lights, mostly the check engine light would come on out of nowhere and then disappear after restarting the car. One thing I forgot to mention in my previous reply, before getting it fixed, I also noticed the issues would get worse in stop-and-go traffic when the engine was really warm. The infotainment would freeze more frequently, and sometimes the climate control would act up too. Looking at your mileage (116224 KM), it's pretty close to when my issues started (around 110000 KM). Just a heads up, when my mechanic was fixing the wiring, they found that heat from the engine had actually caused some of the cable insulation to deteriorate over time. That's probably why the problems were more noticeable when the car was warm. Quick question, have you noticed any correlation between using specific features (like the navigation system or climate control) and when these glitches occur? This might help your mechanic pinpoint the exact location of the faulty wiring more quickly.

Thanks for all that detailed information! After hearing about your similar experience, I'm even more convinced it's a wiring issue in my Z4. What you mentioned about the problems getting worse in stop-and-go traffic really rings true, I've noticed the same thing, especially with the climate control acting up. Come to think of it, I have noticed that using the navigation system seems to trigger more glitches than usual. Sometimes when I try to input a destination, the whole system freezes up, and I have to restart the car to get it working again. The check engine light has been playing peek-a-boo just like you described, popping on and off out of nowhere. I've already called my mechanic and scheduled an appointment for next week. Really hoping it's just the wiring issue like you had and nothing more serious. The deteriorated cable insulation due to engine heat makes perfect sense given the pattern of problems I'm seeing. I'll make sure to mention all these details to help them diagnose it faster. Really appreciate your help on this, it's been driving me crazy trying to figure out what's going on. At least now I have a better idea of what to expect with the repair process!

What do the errors CD9763 and CD9767 mean? MKL is not on. I don't notice anything while driving - the battery was only recently replaced.

(Translated from German)

Check the battery connections to ensure they are secure and free of corrosion, as loose or corroded connections can cause electrical issues. If the problem persists, it might be worth having a professional scan the vehicle for any underlying issues. Let me know how it goes or if you have any further questions!