If I'm reading my Bentley correctly G40 on the 4.0L is cam position sensor Bank 2 (driver's side), not Bank1 (passenger side).
G28 is indeed the engine speed sensor (RPMs) but the Bentley code section doesn't list the location of the sensor - it does for the 1.8T and 2.8.
I will look at the detail of the engine later to see where it might be.
Try posting on theW8forum.dk, and see if anyone is familier with it.
I just had my bank 1 adjuster and sensors replaced under warranty (as well as the thermostat), but mine had thrown the P0011 code.
My extended warranty more than paid for itself that day.