The P0021 code  “A” Camshaft Position  Check Engine Control Module Timing Over Advanced (Bank 2)

This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles, including but not limited to Toyota, VW, Ford, Dodge, Honda, Chevrolet, Hyundai, Audi, Acura, etc. A P0021 code refers to the VVT (variable valve timing) or VCT (variable camshaft timing) components and the car's PCM (powertrain control module) or ECM (engine control module). VVT is a technology used in the engine to allow it to get greater power or efficiency at different running points.   That consists of a few different components but the P0021 DTC specifically refers to the camshaft (cam) timing The "A" camshaft is either the intake, left, or front camshaft. A P0021 engine code is basically the same as a P0011 code, except this is for Bank 2, not Bank 1. Potential Symptoms Most likely a P0021 DTC will result in one of the following: hard starting, poor idle, and/or stalling. Of course, when trouble codes are set, the MIL (malfunction indicator lamp, a.k.a. the check engine light) illuminates. Causes A P0021 DTC trouble code may be caused by one or more of the following: Incorrect camshaft timing Wiring problems (harness/wiring) in intake timing control valve control solenoid system Continuous oil flow to VCT piston chamber Failed timing valve control solenoid  Refer to vehicle specific repair manual to perform component tests for the VCT unit. Notes: Dealer techs have advanced tools and the ability to follow detailed troubleshooting steps, including the ability to test components using a scan tool.