"Unknown Security Code"
Kess V2 can flag up an error saying "Unknown Security Code" when trying to either read or write to the ecu ?
This could possibly mean that the ecu has been flashed before with a BDM tool or maybe someone could of written a NO READ signature into the ecu software when they tuned it..
(WARNING) If you repeatedly attempt to read/write to the ecu and get security code error you can lock the ecu temporarily, to over come this turn the ignition on and leave it for 15 mins before attempting to work with it again
First try allowing a longer period of time between turning the ignition on/off and pressing OK when commanded by K-Suite
If this does not work then try reading with a CMD if you have one
After this if you are still unsuccessful then you will need to BDM the ecu.