DTC what does it mean

DTC = Diagnostic Trouble Code. These are codes that will set to give an indication of what and where the computer detects a problem. However they very seldom actually point to a single component as a failed part.
There are 4 groups of codes that are used in the OBD standards.
P= Powertrain
B= Body
U= Communication and integration
C= Chassis
Each of those has a multitude of codes in each group along with extras that are manufacturer specific. Some of the codes will turn on the check engine light, others will not.