M4 Keyless Entry Dead: Door Handle Electronics Mystery

Hey there! I had a similar issue with my 2015 BMW M3 last month. The door handle sensor was giving me the same headaches, keyless entry stopped working and I got those battery drain warnings too. Turned out the wiring harness in the door handle was damaged, creating a short circuit. The mechanic found corrosion on the connector pins that link the door handle module to the main system. It wasn't just a simple fix like replacing a battery, they had to replace the entire door handle assembly and reprogram the system. This is actually a known issue with these models. It's not catastrophic, but definitely requires a certified BMW technician who knows what they're looking for. They'll need proper diagnostic tools to pinpoint the exact problem and reset the system properly. My advice: skip the general mechanics and head straight to someone who specializes in BMW electronics. The problem will likely get worse if left unattended. Best of luck

Thanks for sharing your experience! That's really helpful. I'm actually planning to take it to a BMW specialist this week based on your advice. The symptoms sound exactly like what I'm experiencing. Quick question, do you remember roughly how much you ended up paying for the fix? Also, has everything been working smoothly since the repair? Just want to know what I'm getting myself into. Cheers!

Hey again! Just wanted to follow up, glad I could help! After seeing the BMW specialist I mentioned, my issue turned out to be way simpler (and cheaper!) than what I initially went through with my M3. It was just a faulty cable connection in the door handle assembly, nothing major like my previous repair. The whole thing cost me 95 € to fix. They just had to sort out that cable connection, and honestly, it's been working perfectly since then. No more keyless entry problems or those annoying battery warnings. The car's back to normal, just how it should be. Much better outcome than when I had to get the whole handle assembly replaced last time! Really happy I recommended you go to a specialist, these electronics can be tricky, but when you've got someone who knows what they're doing, it makes all the difference. Let me know how yours turns out, hope it's a simple fix like mine was this time around! Cheers!

Wanted to update everyone, just got back from the BMW specialist and I'm so relieved! The issue was indeed with the door handle wiring, but thankfully not as complex as some other cases. The technician was super knowledgeable and spotted the problem right away. They fixed a loose connection in the wiring harness and replaced a couple of corroded pins. Total bill came to about 120 bucks, way less than I was expecting after hearing some horror stories! The keyless entry is working perfectly now, and all those annoying error messages are gone. Really glad I took your advice about going to a specialist rather than my old mechanic. They even showed me exactly what was wrong and explained everything clearly. The whole thing took less than two hours. Thanks again for pointing me in the right direction. If anyone else runs into similar issues with their BMW, definitely skip the general mechanics and go straight to a specialist. Saved me both time and money in the long run!