GM Genuine Parts Engine Variable Valve Timing Solenoids are designed, engineered, and tested to rigorous standards, and are backed by General Motors. These solenoids regulate oil flow to the cam phasers that change the timing of the camshafts. The desired positions of the camshaft varies with engine speed and load and is calibrated for optimal engine performance, drive quality, and efficiency. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE).