I've noticed ever since upgraded to the latest beta, a whole lot of DTC's are now grey'd out that weren't before. To the point you can't even put a set of headers on a car anymore without check engine lights because all the DTC's that need to be disabled can't be.
EDIT: Just checked a tune on an older version. ****DO NOT UPGRADE YOUR SOFTWARE. YOU WON'T BE ABLE TO TURN OFF ANY OF THE DTC'S THAT NEED TO BE DISABLED FOR MODIFYING THESE CARS. DO NOT UPGRADE***