2002 Infiniti I35 Question: Engine light is on. OBD code 0011 shows up. Car has 84,000 mi.

code 0011 is possible bad camshaft position sensor?
Where is this located on the engine and is there
1 or 2 sensors? Engine oil is clean and changed every
3,000 mi.Also it could be an intake valve timing
control solenoid? where is that located? are these 2 items easy to change?

Thanks GFO