It's not identical part numbers, they have different letters at the end - but I've opened each one of them up to regrets the gears and I can confirm they are all identical parts for sure.
They have all been rotated and the fault has stuck with the same side, left side actuator - and it has always behaved the same whichever of the parts I have used at that time.
I unplugged the manifold runners as you suggested, gave it sometime and started the ignition... the turbo definitely did a sweep in this instance!
I don't have a code reader but my neighbour does - and these faults will not clear. As soon as you clear and start the ignition, they're all instantly back on.
I genuinely think there is an electrical issue and it is not as simple as I had hoped anymore.
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In other news, I've ordered the new car regardless of this trade in... I'm too tired stressing over the Audi! Welcome to the world of the Mercedes S Class
