I'd also wonder if there is a vacuum leak (something unplugged or not seated correctly) or a sensor not plugged in. Did you plug your car into a Peak tool, INPA, GT1 or similar to read your codes? The car IS working to tell you something - you just need to find a way to speak it's language

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2002 Euro X5 (E53) 3.0 diesel (M57)
5 speed manual with UUC short shifter.
Pre-xDrive NV125 transfer case (chain & gears).
Factory Xenon headlights, Spyder LED tail lights
Updated vortex crankcase breather.
Motorsport dead pedal, factory fire extinguisher, factory first aid kit, factory F&R mud flaps, factory PDC

Bilstein B6 shocks F&R
Redline oil has replaced "lifetime" fluids (F&R diff, manual transmission, transfer case and P/S).
Dimple magnetic drain plugs in all compartments.