P0016 is an intake cam position fault. It's conditions are such that it will normally set right at start up (600-1500rpm, 20c-88c coolant temp), particularily if the car has been shut down recently, but not fully cooled. The oil control valve must be in the off position to set this dtc.
Assuming you timed the cams correctly, here is why this happens:
The mivec actuators are not a "flow through" system. When changing cams, it is important to force the air out of the actuators when installing the cams. Failure to do so allows air to be trapped in the actuator. When you shut down the car, this air expands, moving the cam. The car then sees this on next start up as a cam position error. Eventually the air will work its way out, and this code should go away.
If there is any doubt as to whether your cams were timed correctly, pull the valve cover and check. 90% of time, pumping the actuator with an oiler after installation onto the end of the camshaft will prevent this, and its other associated codes. The other 10% will get this code no matter what, and you just have to wait for the air to get out of the system.
