Thanks , not sure i'll find mechanic able to dive into such depths troubleshooting out here, let alone fix it, hence the proposed action lets do the oil service kit at your own risk with 30% chance of success, and besides crawled under X this morning there was no sign of the underbelly splash plates etc being removed, and on diesel without removing these gubbins a leak cant be visaually detected (according to Wpoll..so begs question why he said its a slow leak and fluid is dirty black.....he never checked level full stop, or else would have seen tell tale fingerprints etc etc on parts removed to be able to check this)

Gave it a quick spin 10mins this am, ok no error but means nought, will seek out another opinion, as dont want to start throwing parts at it, In meantime have found one mechanic willing to take a peek at short notice and despite me telling him the displayed code has been wiped by another garage..chucking scanner tool on it alone is not what i want, i want them to verify no leak for a start and take it from there

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