BMW X5 Keyless System Failure, Diagnosis Help Needed

Hey! Got some experience with a similar issue on my 2003 BMW 3 Series (and I've also owned an X3). I'd say I have some basic car maintenance experience. Had the exact same symptoms, remote died and dashboard lit up like a Christmas tree. Thought it was something major, but my trusted mechanic checked it and turns out it was just a dead battery in the key fob. Cost me 37 Euro for the battery replacement and reprogramming. Whole thing took about 30 minutes. But before jumping to conclusions, could you share: Are you still able to start the car with the physical key? What exact warning message are you seeing? Have you tried using your spare key? This might help narrow down if it's really just a battery issue or something more complex with the electronic system.

Thanks for the detailed response! Just had my latest service done and everything was fine then (currently at 26720 KM). Yes, I can still start it with the physical key, thankfully. The warning message shows "Key fob system malfunction" and my spare key's doing the same thing. Tried both keys actually, and neither remote function works. Really hoping it's not the whole control module, that'd be pretty expensive! I'll probably take it to my mechanic next week, but wanted to check if anyone here had dealt with something similar first.

Hey again! Thanks for the extra details about your BMW, that actually helps a lot. Since both your keys are acting up the same way, I'm starting to think this might not be just a battery issue like I had with mine. When I had my 3 Series problem, only one key was affected. In your case, since both keys are failing and you're getting that specific "Key fob system malfunction" message, it's sounding more like it could be the key reader or the control module itself. On my old X3, I actually ran into something similar, turned out to be a faulty antenna ring around the ignition switch that reads the key signal. Cost me about 400 bucks to fix, but at least it wasn't the full control module. My suggestion would be to get it checked out by your mechanic as planned. Your mileage is pretty low at 26720 KM, so that's a bit unusual for this type of issue to pop up. When you take it in, make sure they check the antenna ring and the key reader first before jumping straight to replacing the whole control module. Would you mind keeping us posted on what they find? Always good to know for future reference, plus I'm genuinely curious if it's the same issue I had!

Thanks for all that info! You've actually made me feel a bit better about the whole situation. I was dreading having to shell out for a new control module, but hearing about your antenna ring issue gives me hope it might not be as bad as I thought. That 400 price tag sounds way better than what I was imagining for a full module replacement! You're right about the mileage being low for this kind of problem, honestly, that's what had me worried in the first place. I've got my appointment scheduled for next Tuesday morning, so I'll definitely keep you posted on what they find. Really appreciate you sharing your experience with both the 3 Series and X3, it's giving me a better idea of what to ask them to check. The antenna ring theory makes a lot of sense since both keys are acting up the same way. I'll make sure to mention that specifically when I take it in. Fingers crossed it's something similar to what you encountered! I'll update the thread once I know more. Thanks again for taking the time to help me figure this out!