Peter,
I don't whether this may help, but your OBDii reader may be not compatible.
The car does NOT need to run to read DTCs from the vehicle, just ignition on.
P0001 is an uncommon DTC, not used by many manufacturers.
P0001 Fuel Volume Regulator Control Circuit/Open OBDII Engine Light Trouble Code | Engine-Codes.com
Certainly not in the DTC list for GM LS engines as noted from Holden SI.
I work as a Senior Tech for a Holden dealership in Brisbane.