When the error code P0622 OBDII is stored it means that the Power Train Control Module (PCM) has observed a malfunction in the generator field coil control circuit. The letter F indicates that the field coil control circuit is defective.
The field coil is around the generator armature and remains in the alternator housing. The PCM constantly checks the continuity and also voltage level of the generator field control circuit whenever the engine is in action. The generator field coil is a fundamental part of the correct operation of the generator and also maintains the battery charge levels.
Each time the vehicle is turned on and the PCM is activated, multiple driver self-tests are performed. Also, through the Control Area Network (CAN) the internal controller is self-tested to compare the signals from each module. If a problem is found in the generator field control circuit, the DTC code P0622 OBD2 is set and the Check Engine light is illuminated.