BMW i8 Key Problems? Common Fix For Dead Entry System

Hi there! I've got some experience with BMWs and had a similar issue with my 2016 BMW i3. My 740e also had this problem once. I was getting the same symptoms, keyless entry stopped working out of nowhere. Turned out it was just the key fob battery dying. Took it to my regular workshop and they confirmed it with their diagnostic tool. The fix was super simple, they just replaced the battery in the key fob. Cost me 37 Euro for the battery replacement and diagnostic check. Before you head to a workshop, could you share: Does the physical key still work when you take it out? Are you getting any specific error messages? Have you noticed the key becoming less responsive recently? With these details, I might be able to help confirm if it's the same issue I faced.

Thanks for sharing your experience! Those are helpful suggestions. Just had my last service at 33273 KM, and everything was fine until this issue popped up. The physical key actually works when I insert it, but the keyless function is completely dead. The dash shows "Key not detected" when I try to start the car without inserting the key. Hadn't noticed any gradual decline in responsiveness, it just stopped working suddenly yesterday. I'm hoping it's just a battery issue like yours was, sounds much better than having to deal with more complex electrical problems. Has your fix held up well since then?

Hey again! Thanks for the follow-up. Yeah, those symptoms sound exactly like what I experienced with my i3. Since you mentioned the physical key still works and you're getting that "Key not detected" message, I'm even more convinced it's the battery. The fix has held up perfectly since then, it's been about 18 months now with no issues. Actually, the workshop told me these key fob batteries typically last 3-4 years, so the timing makes sense for both our cars. They recommended keeping a spare battery at home just in case, which I thought was smart. One thing I noticed before my key completely died, try pressing the lock/unlock button from different distances. If it works close up but not from the usual distance, that's another sign it's definitely the battery. Quick tip from my experience: if you do get the battery replaced, make sure they sync the key properly afterward. My first replacement worked fine for keyless entry, but I had issues with some comfort settings until they did a proper sync. Hope this helps confirm what you're dealing with. Let us know how it turns out!

Thanks so much for all the detailed help! I just got back from the workshop and you were absolutely right, it was just the key fob battery. They did exactly what you mentioned, replaced the battery and synced everything up. Cost me about €45 total, which isn't bad at all. The keyless entry is working perfectly again, and all my comfort settings are intact too. I followed your advice about getting a spare battery. The technician showed me how to replace it myself if needed, though he mentioned it's best to let them handle the sync process if I do change it at home. Really appreciate you taking the time to share your experience, saved me a lot of worry about potential electrical issues! Nice to know these batteries typically last 3-4 years too, helps me plan ahead. I'll definitely keep an eye on the response distance going forward, that's a great tip for catching it early next time.