The Camshaft Position Sensor (CMP) is used to know the position of the camshaft. This information is then sent to the Powertrain Control Module (PCM), which uses it to control the injectors and in some cases, depending on the vehicle model, to measure the ignition time. On the other hand, the Crankshaft Position Sensor (CKP) informs about the position of the crankshaft, in addition to the engine RPM to the PCM. This information is used to control ignition timing and also to control fuel injection.
The crankshaft and camshaft are connected by a belt or timing chain and are thus synchronized. Both the CMP sensor and the CKP work in harmony to give continuous information to the PCM about engine time. If synchronization is not activated, the DTC code P0018 OBDII is set and the Check Engine light is illuminated.