The diagnostic code P0204 OBD2 indicates that the Power Train Control Module (PCM) has detected a fault in one of the injectors or even this fault can be caused by one of the cables leading to the sensor. The injector is monitored by the Powertrain Control Module (PCM) and when it is activated, the PCM expects the injector voltage to be low or close to zero.
When the injector is off, the voltage should have a high voltage or close to the battery voltage. In case the voltage is not within the expected levels, fault code P0204 is established. It should also be noted that this code is established if the result is that the resistance of the circuit is low or high excessively.