When the vehicle has fuel injection in sequences, the PCM (Power Train Control Module) controls each injector individually through a controller. The PCM supplies the ground circuit to each of the injectors. In addition, each of these circuits is monitored by the vehicle’s computer in search of faults.
When the PCM commands an injector to shut off, it expects to see a high voltage in the controller’s ground circuit. On the other hand, when the injector is instructed to turn on, it expects the voltage in the controller circuit to be low. If the PCM does not observe these expected conditions in the controller circuit, the DTC code P0200 OBDII is stored.