The engine P203B Code tells of the car engine problem and it is important to know the correct meaning for fix the car engine. It is necessary to check the car engine for finding the right reason of the car engine problem. However, there are some causes may found in the car engine problem and by the accurate verification, it is easy to know about the car engine problem. The engine code P203B OBD2 exactly refers to the camshaft (cam) timing. In this case, if the cam timing is over retarded, the engine light will be illuminated and the code will be usual.