Follow the troubleshooting steps in the FSM
https://www.nicoclub.com/service-manual ... 3%2FEC.pdf
See Page EC-186
< DTC/CIRCUIT DIAGNOSIS >[VQ37VHR]P0011, P0021 IVT CONTROLP0011, P0021 IVT CONTROLDTC LogicINFOID:0000000008291245DTC DETECTION LOGICNOTE:•If DTC P0011 or P0021 is displayed with DTC P0075 or P0081, first perform the trouble diagnosis forDTC P0075, P0081. Refer to EC-196, "DTC Logic".•If DTC P0011 or P0021 is displayed with DTC P0524, first perform the trouble diagnosis for DTCP0524. Refer to EC-384, "DTC Logic"
Crankshaft position sensor (POS)• Camshaft position sensor (PHASE)• Intake valve control solenoid valve• Accumulation of debris to the signal pick-up portion of the camshaft• Timing chain installation• Foreign matter caught in the oil groove for in-take valve timing control