The diagnostic code P0012 OBD2 refers to components of the VVT system (Variable Valve Timing). This system is used with the objective that the engine obtains an efficiency or greater power, in several points of operation.
Although the system consists of several components, in this case the DTC code P0012 specifically indicates that the problem lies in the timing of the camshaft. Indicates that the timing of the cam is taking longer than it should. The camshaft A is the front camshaft located in the bank number one, this corresponds to the side of the engine that contains the cylinder number one.