Ok another one for me to keep an eye out for, but if it is any consolation I had this issue once (injector failure error) but car still ran and odd errors like dsc off, it was my battery! and my battery was low due to a supposedly known starter motor issue (drawing too much current on each startup causing more juice loss than could be replenished by an average daily drive)

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E53 X5 3.0d SUV prod.date 11/2004 eng.variant M57N Europe Right hand drive N