Porsche 991 Cold Start Problems, Failing Battery Sensor?

Hey there! I had a similar issue with my 2019 Porsche Cayman (I've got some experience working on cars, but I'm no expert). The symptoms you're describing sound exactly like what I dealt with last winter. After getting fed up with those annoying cold starts, I took it to my local Porsche workshop. Turned out the battery sensor microprocessor was shot, it wasn't reading the battery status correctly, causing all those starting problems. Cost me about 315€ to get it fixed, including parts and labor. The repair took about 2 hours, and it's been running like a charm since then. What's the mileage on your 991? Also, have you noticed any warning lights on the dash? This info could help confirm if you're dealing with the same issue.

Thanks for sharing your experience! My 991 has 37178 KM on the clock, and it was serviced not too long ago. I haven't noticed any warning lights on the dash yet, but those cold start issues are really starting to worry me. That's interesting about the battery sensor microprocessor, definitely sounds similar to what I'm experiencing. Did you notice if the problem got worse over time before you got it fixed? I might head to my local Porsche dealer this week to get it checked out, especially since the temperature's dropping lately.

Hey again! Yeah, I totally remember when I had this issue with my Cayman. To answer your question, yes, the problem definitely got worse over time. It started with just slightly longer cold starts, but within a few weeks, it became really unpredictable. Some mornings the car would start fine, and others it would struggle or not start at all. With your mileage being pretty low (mine was around 42000 KM when I had the issue), and no warning lights, it's even more likely to be the battery sensor microprocessor. I actually waited longer than I should have before getting it fixed, kept thinking it might just be the cold weather or something. Big mistake! The problem just got more annoying. Quick tip from my experience, when you take it to the dealer, ask them to specifically check the battery management system. My mechanic initially thought it was just a weak battery until I insisted on checking the sensor based on what I'd read online. Saved me from unnecessarily replacing the battery. Hope this helps! Let me know how it goes at the dealer. These 991s are great cars when everything's working right!

Thanks so much for that detailed advice! I really appreciate you sharing your experience, especially about how the problem got worse over time. You've convinced me not to wait around, I've already called my Porsche dealer and scheduled an appointment for this Thursday. I'll definitely mention the battery management system specifically, as you suggested. It's super helpful to know that it might be misdiagnosed as just a weak battery. The fact that your Cayman had similar symptoms at a comparable mileage makes me feel more confident about what I might be dealing with. I'll update the thread once I get it checked out, in case anyone else runs into similar issues. Thanks again for all the help!