Diagnostic code P0339 OBDII indicates that the Powertrain Control Module (PCM) has found an erratic or intermittent voltage signal from the Crank Position Sensor (CKP). When an OBD2 system uses multiple CKP sensors, the sensor “B” refers to sensor number two.
The CKP sensor monitors both engine speed and crankshaft position. The position of the crankshaft is important, as it is used by the PCM to calculate the ignition spark timing. The crankshaft position sensor (CKP) has a slip ring that passes very close to its magnetic tip as the crankshaft rotates. When this happens, an electromagnetic circuit is completed which briefly interrupts the circuit. These circuit interruptions are recognized by the PCM as a wave pattern, which represents voltage variations.
The input signals of the CKP sensor are constantly monitored by the PCM. If the input voltage turns out to be below the set level for a period of time, the DTC code P0339 is set.