The OBD-II P0517 code is a code that is seen after scanning your vehicle’s diagnostic system. An OBD-II P0517 code means that the engine control module (ECM) has detected a high voltage reading from the battery temperature sensor circuit. Generally the normal voltage reading that the ECM should be receiving should be around 5 volts.
To read the battery temperature, a 5 volt reference signal is sent from the PCM to the battery temperature sensor, which is grounded through the sensor return circuit. When the battery temperature increases, it decreases the sensor resistance and the ECM will receive a voltage signal that is higher. When the battery temperature decreases, the voltage signal sent to the ECM decreases.