BMW X4 Key Fob Failure, Quick Fix or Major Repair?

Had the same problem with my 2013 BMW X3 last year. Started with intermittent key fob issues, then got worse until I had to use the physical key. Turned out the cable connection to the comfort access antenna was corroded and partially disconnected. The mechanic showed me where the wiring harness had deteriorated near the trunk area. It wasn't just the antenna, there was also some water damage to the connection points. They had to replace the wiring harness and the antenna module. It wasn't a major repair in terms of car safety, but it needed fixing to restore proper functionality. The comfort access system is pretty complex on these BMWs, and when one part fails, it affects the whole system. Just make sure whoever works on it knows BMW systems well, these electronic issues need proper diagnostic equipment to fix properly. My problem got solved in one visit, and it's been working perfectly since then.

Thanks for sharing your experience! That's really helpful since it sounds exactly like what I'm dealing with. The corrosion issue makes total sense given the symptoms. Quick question though, do you remember roughly how much you ended up paying for the repair? And has everything been working smoothly since then, or have you noticed any other electrical quirks popping up? Just want to know what I might be getting myself into with this repair.

Hey there! Just wanted to follow up on your question. I paid 95 € for the repair, which was mostly labor costs since they had to properly diagnose and fix the cable connection issue. Much cheaper than I initially feared! Since getting it fixed at the mechanic, everything's been working perfectly, no more key fob drama or having to use the physical key. The bumper antenna is working like a charm now. Honestly, it was such a relief getting it sorted. No other electrical issues have popped up either, so it really was just that isolated problem with the corroded connection. I know exactly what you mean about wanting to know what you're getting into. But in my experience, once they fix that antenna connection properly, you should be good to go. Just make sure you get a mechanic who knows their way around BMW electronics, it makes all the difference when dealing with these kinds of issues.

Just got back from the mechanic and wanted to update you all! Turned out you were spot on. They found corrosion in the wiring harness and had to replace both that and the antenna module. The bill came to around 90 €, which was honestly a relief considering I was expecting much worse. The whole process was pretty smooth, dropped it off in the morning and got it back by afternoon. Used a specialist who really knew their BMWs, and they walked me through exactly what was wrong. No more fumbling with the physical key or dealing with that annoying error code! Really appreciate everyone's input here. It helped me feel more confident about what needed fixing and saved me from potentially getting overcharged. Car's running perfectly now, just like when I first got it. Best part? The technician gave me some tips to prevent future corrosion issues. Nice to have this headache behind me finally!