BMW 8 Series Power Seat System Malfunctioning

Hi there! I've got some experience with BMWs since I had a similar issue with my 2018 BMW 7 Series (also worked a bit on my M5). I'd say I have low experience, mostly learning through dealing with my own car issues. This sounds very familiar, my seats were acting up just like yours. Turned out the battery was heavily discharged, which messed with the power seats and other electrical systems. Took it to my regular workshop, and they diagnosed it properly with their BMW diagnostic tool. The whole thing, including a new battery and reprogramming, cost me about 290 Euro, but it fixed the issue completely. Before you head to a workshop though, could you share: Does this happen consistently or intermittently? Are you getting any other electrical issues (like with windows or mirrors)? Which error codes are you seeing exactly? This might help narrow down if you're dealing with the same battery-related problem I had or if it's something else in the electrical system.

Thanks for the detailed response! My 8 series just hit 67951 KM, and I had its latest service about three weeks ago. The seat issue happens every single time, super consistent. No problems with windows or mirrors, which is weird. The error code I'm getting is "Seat Module Malfunction" but only for the passenger side. I checked the battery voltage yesterday, and it's showing normal readings, so I don't think it's battery-related like in your case. The driver's seat works perfectly fine, which makes me think it might be a module issue specific to the passenger side. Would you know if there's a way to reset the seat module without special tools? Really trying to avoid a costly workshop visit if I can sort this out myself.

Hey again! Always happy to help a fellow BMW owner. Yeah, after reading your details, I can see this is different from my battery situation. With those symptoms, especially the consistent passenger-side-only issue and that specific error code, I actually had something similar happen later with my 7 Series. In my case, it turned out to be a faulty seat control module on the passenger side. I tried the DIY reset route first (disconnected the battery for 30 minutes, hoping for a miracle), but no luck. These modern BMWs are pretty sophisticated, and unfortunately, some fixes just need proper diagnostic equipment. I ended up having to take it to my regular workshop anyway. They found that water had gotten into the seat module connector under the passenger seat, apparently more common than you'd think. The fix involved replacing the module and resealing the connection point. Cost me around 400-500 Euro total, but at least it's been working perfectly since then. Based on your symptoms being so similar to what I experienced, I'd say you're probably looking at the same issue. I know it's not what you wanted to hear, but these seat modules usually need professional attention. Trust me, I learned the hard way trying to fix it myself first! Want me to share what the repair process was like? Might help you know what to expect if you do need to take it in.

Thanks, that actually helps a lot, even if it's not the news I wanted to hear! Your experience with the water damage is particularly interesting since I recently noticed some dampness on the passenger floor mat after a car wash. Didn't think much of it at the time, but now it makes sense why only the passenger side is affected. I appreciate you offering to share more about the repair process, but I think I'll bite the bullet and book it into the workshop. No point risking more damage trying to fix it myself, especially since water might be involved. I'll make sure to mention your experience to them, could help them diagnose it faster. Just one last question, did you notice any long-term issues after your repair? Want to make sure this won't be a recurring problem once fixed. Really appreciate all your help with this!