BMW X3 Power Seats Only Work After Engine Start, Help!

Hi there! I have some experience working on cars and had a similar issue with my 2010 BMW X1 (also happened to my 's X5). The symptoms were exactly the same, power seats not working until the engine was running. Turned out the battery was severely discharged and couldn't provide enough power for the seat mechanisms. My trusted mechanic ran a full diagnostic and confirmed the battery was the culprit. Had it replaced for about 290 Euro and that fixed everything. Could you share what error codes you're getting? Also, have you noticed any other electrical issues like slow engine cranking or dim lights? This info would help determine if you're facing the same problem. The battery-related problems can be tricky to diagnose since they affect different systems. Let me know these details and I might be able to help further!

Thanks for sharing your experience! My X3 just hit 121355 KM and had its last service about 2 months ago. The symptoms sound similar, but I'm not seeing any other electrical issues, engine cranks normally, all lights work fine, and even the memory function remembers the positions, just won't move until the engine's running. Got error codes 93AC4 and 93AC8 from my OBD scanner which point to the seat module specifically. I'm thinking it might be more than just a battery issue in my case, but I'll definitely get it checked. Did your mechanic mention any other potential causes during diagnosis?

Hey again! Thanks for those extra details about your X3. You're right, this does sound different from what I experienced with my X1. When I had my battery issue, I definitely noticed other electrical gremlins, which you're not seeing. Those error codes you mentioned are actually really specific to the seat module, unlike my more general electrical issues. Looking back, my mechanic did mention that if it wasn't the battery, the next likely culprit would've been the seat control module itself or the wiring harness underneath the seat. In your case, since everything else is working fine and you're getting those specific seat module codes, I'm starting to think I was off with my initial battery suggestion. My who works on BMWs recently told me these seat modules can get temperamental with age and sometimes need replacing. Just curious, have you tried disconnecting the battery for about 15 minutes and then reconnecting it? This helped temporarily with my issues before I discovered it was the battery, but it might also tell us if your module needs a reset or if it's actually failing. Either way, those error codes are pretty telling, might be worth having a BMW specialist take a look at the seat module specifically.

Thanks for the followup and detailed explanation! I actually tried the battery disconnect trick last night, didn't help unfortunately. You've convinced me this is probably the seat module itself rather than a battery issue. The error codes matching up with seat module problems and the lack of other electrical issues really does point that way. I've scheduled an appointment with my mechanic for next week. I'll make sure to mention your experience and ask them to specifically check the module and wiring harness. Really appreciate you taking the time to share your knowledge and walk through the troubleshooting steps with me. I'll definitely update once I get it sorted out in case anyone else runs into similar issues with their X3. The seat module replacement sounds expensive, but at least I'll be going in with a better idea of what to expect!