The OBDII is a standardized, automated framework which the USA EPA had approved and installed into its whole year of modeling (MY) 1996 and then into modern light-duty vehicles and trucks, recognized as "on-board diagnostics II."
The DTC framework is a set of problematic diagnostic codes that used alert you if a vehicle is unable to operate using an on-board Diagnostic System.
If the system of the automobile identifies a problem, a special DTC code is generated as well as a position sensor is sent to the instrument cluster, that's why Technician B is correct.
