The engine U2001 OBD2 definitely denotes to the camshaft timing. In this case, if the cam timing is over-retarded, the engine light will be illuminated and the code will be established. The deactivation of cylinders is realized by releasing a synchronizer pin that generally meshes the cam follower and rocker arms. The engine U2001 code solves the synchronizer pin which is unconfined using hydraulic pressure which is measured by a dedicated solenoid. Do not follow any meaning of the code for fixing the car engine problem. The right meaning of the code is found in the car engine manual and read the car manual.