DTC P1397: Camshaft Position (CMP) Sensor 2 Signal Implausible, Short Circuit to Ground, Short Circuit to Plus: Function

The CMP sensor 1 signal identifies the first cylinder. If both the crankshaft position (CKP) sensor signal and the CMP sensor signal coincide, this signifies the timing point for cylinder 1. Recognizing cylinder 1 is needed for sequential fuel injection and knock sensing.

The CMP sensor 2 is needed to identify the position of the camshaft for cylinders 4 - 6.