[masraum]

I think the deal is that back when OBDII was created, (in the 90s) the amount of computerized data was limited. These days there's a LOT more stuff in cars that's computerized, and manufacturers have added their own stuff. Think about the fact that there's now computerized suspension, transmissions, TPMS, multiple air bags, windows, etc... that were not computerized in the 90s. I suspect that instead of updating the OBDII standard to include all of these new things, the various manufacturers just added their own stuff. So now your scanner/diagnostic tool needs to support the proprietary codes for any manufacturers that you want to scan.