What scanner are you using? I found BMW specific scanners to be preferable to generics for the most part.
A battery going bad can cause all kinds of errors.
Others will have better opinions than I.

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2001 x5 3.0 (sold with broken motor), 1990 e30 M3, 1991 318is, 2002 325i, 2008 335i Dinan stage 3 6 speed,