Z4's Xenon Lights & Electrical System Going Haywire

Hey there! I had very similar issues with my 2015 BMW M4 last year. The xenon lights changing color and electrical gremlins are usually connected to the voltage regulator or a failing control module. In my case, it turned out the main wiring harness had some corroded connectors near the headlight assembly, and there was a loose ground connection. I initially thought it was just the xenon bulbs aging, but when the speedometer started acting weird too, it was clear something bigger was going on. The garage found multiple connection points that needed cleaning and resealing. They also had to replace the voltage regulator since it wasn't maintaining stable power to the systems. This isn't a quick DIY fix, it needs proper diagnostic equipment to pinpoint the exact issue. While it's not engine-threatening serious, it's definitely something you want to address soon since electrical issues tend to get worse and can affect other systems. I'd skip the general mechanics and go straight to someone who specializes in BMW electrical systems. These symptoms are pretty typical of voltage/wiring issues in these models.

Thanks for sharing your experience! Sounds exactly like what I'm dealing with, glad to hear I'm not alone with these electrical quirks. Just curious, do you remember roughly how much the whole repair set you back? Also, has everything been working fine since the fix, or have you noticed any other electrical oddities popping up? Really appreciate the advice about going to a BMW specialist, seems like these electrical gremlins need someone who really knows what they're doing.

Hey again! Just wanted to give you a quick update since I saw your questions. After getting it fixed by the specialist, everything's been running like a charm! The turn signals that were giving me grief? Totally sorted now, turned out it was just a faulty cable connection that needed replacing. The bill came to 95 € for that particular fix, which honestly wasn't as painful as I'd expected. The best part? Haven't had a single electrical gremlin since they sorted it out. My M4's been performing perfectly, no more purple lights, no weird speedometer messages, nothing. Really glad I went with a BMW specialist like I suggested to you. These guys know exactly what they're looking for and don't waste time with trial and error. Just keep in mind that while my issue turned out to be relatively straightforward with the turn signal, your total cost might differ since you're dealing with multiple symptoms. But trust me, getting it done right the first time by someone who knows BMWs inside out is worth every cent. These electrical issues can be tricky, but once they're properly fixed, they usually stay fixed!

Thanks so much for the detailed follow-up! I actually just got back from a BMW specialist who fixed my Z4, and wow, what a difference! Had almost the exact same issue, corroded wiring harness and a wonky voltage regulator. They cleaned everything up, replaced some connections, and now my car's running perfectly. The purple lights are gone, speedometer's back to normal, and those annoying turn signal issues have disappeared completely. Cost-wise, I lucked out, the whole repair came to less than I'd feared. Much better than throwing money at unusual fixes that might not have solved the problem. Really glad I followed your advice about skipping the general mechanics and going straight to a specialist. They diagnosed it in no time and knew exactly what needed fixing. Thanks again for pointing me in the right direction. Definitely saved me from a lot more headaches down the road!

All lights are working, I’ve replaced with LEDs; I have deactivated the alerts and faults still appear

Hello Ztech2001, Since you've already checked bulbs and alerts, inspect the wiring harness and connectors to the lighting system for any corrosion, damage, or loose connections, as these could trigger fault messages even if lights function normally. Could you update me after checking this? Let me know if you have any further questions.