The code P0021 OBD2 refers to the components of the Variable Valve Timing system (VVT) or Variable Cam Timing (VCT).
The VVT (Variable Valve Timing) technology is used in the engines, with the aim that this one obtains more power in its different points of operation.
The code P0021 specifically indicates that the timing of the camshaft is above the limit already established. The camshaft A is the intake camshaft, being left or forward. This diagnostic code is similar to P0011, unlike that P0021 specifies that it is for bank 2.