How can I tell if my VVT engine components are defective?

Well, this is an impressive list. Here we go: P0022 and P0021 mean you need to change the oil and use recommended weight, but first you probably have a failed oil control valve that needs replaced. Next, oxygen sensor Bank 2 Sensor 2 is throwing a code and may need replaced. Lastly, probable bad thermostat or coolant temperature sensor. When this work is done, the last code P0018 should go away with the other repairs. Good luck!!