I believe the seat sensor will trip a code. I had no codes read by my Peake SRS code scanner, just a faintly glowing light that would come and go. The other problems listed by the OP could be switch or even battery related. The switch cost me $36 in Bavauto (?) and I was charged one hour by the indy who fitted it. No problems since.

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2021 X5 xDrive40i
2015 X5 xDrive35i MSport
(Traded) 2013 X5 xDrive35i