Technical solutions are described for determining a sensor failure in a motor control system with at least three phase current measurements. An example system includes a current controller to generate an input voltage command for a motor using feedforward control. The system further includes a failed sensor identification module that, in response to the current controller operating using the feedforward control, determines that a current offset error is indicative of a failure of a current sensor, the current offset error determined based on a magnitude and a phase of a diagnostic current. Further, the failed sensor identification module identifies the current sensor experiencing the failure based on a phase value of the diagnostic current in response to the failure.