Q: P0016 and P0018 keep popping up.

Hi, thanks for writing in. These codes are both camshaft and crankshaft correlation codes. While these codes can be caused by a faulty sensor, more often they indicate a problem with the engine timing components. This could be anything from a stretched timing chain to a failed oil control valve, as you mentioned. The oil control valve solenoid is used to apply hydraulic pressure to the camshaft actuators to adjust engine timing. A problem with the engine timing can result in engine damage, so I suggest you have a professional, such as one from YourMechanic, diagnose this problem as soon as possible.