Let's see if I can
help. OBDII (or as the poster put it OBD2) is an emissions standard that was implemented in California and adopted world wide. OBDII defines the hardware and the communications for performing emissions related diagnostics. It does not require the manufacturer to report faults found in the car that do not effect emissions. For this reason, OBDII is limited.
The VAG cars have another protocol in them that is specific to them and far more detailed than what is reported via OBDII. The VAG designers limit the OBDII information presented to only the emissions related faults.
A factory level tool that uses the VAG protocols will communicate with everything in the car.
Now to add to all the confusion, OBDII originally had two hardware protocols - one used a pulse width modulated technique and the other used a different hardware technique. The US manufacturers used the PWM method. The Europeans used the other method. The Asians were split.
In 2008, the US government mandated that all vehicles sold in the US would now have to be on one standard - the CAN bus standard. (CAN = Controller Area Network) So, all manufacturers started a move to CAN beginning around 2003.
Ross-Tech's KEY series interfaces do not support CAN. Our older HEX series interfaces which have been out of production since 2004, did not support CAN. In 2004 we introduced the HEX+CAN series interfaces to cover the need for CAN based VAG cars. In 2007 we introduced the MicroCAN interface that was designed for the MK5 CAN based cars as a lower cost enthusiast product.
OBDII will never give the user all the information they need to keep their car on the road. It will
help with engine running issues but not all.
