The oil feed on the pass side head is 1 port, that 1 port branches to 2 lines, 1 line to avcs ocv, and 1 to turbo. the avcs ocv regulates the oil delivery to it to fill the cam up with oil making its rotational speed slightly slower thus "valve timing" adjustments. The cam position sensor detects this and equates a duty cycle to an expected cam position change.
no oil flow to it = no change in cam timing since no oil is filling and changing the cam speed (ever so slightly due to increased mass, our cams are almost completely hollow). when the ecu wants to advance the avcs intake timing, the ocv closes and reduces oil flow into the cam thus making its rotational speed slightly faster (^ timing). as the ecu's AVCS timing table calls for ocv open/closure, the ecu expects the cam position sensor to confirm this change.
the code 0021 and 0011 can come from either the avcs oil supply being restricted or the ocv solenoid itself is bad. if the code if for the passenger side, keep in mine the turbo is fed by the same line as the avcs, thus if it is infact oil restriction causing the code, the turbo integrity is at risk too.