S80 Auxiliary Battery Alarm Error

I had something similar with my S80. The alarm would randomly go off, and sometimes not arm at all. Check the voltage on that auxiliary battery; they're notorious for failing. It's a pain, because if it's dead or dying, it throws all sorts of weird codes.

Thanks for the info. Was it also showing in the error memory? And did you replace the battery yourself or have it done?

Yes, the error was definitely showing, something about the alarm system having low voltage or a communication fault. I tried fiddling with it myself, but honestly, access is tight, and I didn't want to mess anything up. I ended up taking it to a workshop. Best to have it diagnosed properly, especially with electrical issues.

OK, thanks for confirming. I took it to the shop; auxiliary battery was indeed the culprit. Repair came to 330€, including the new battery and diagnostic. Appreciate the help!