The P0715 OBD2 is a diagnostic code that refers to a fault in the ISS (Input Speed Sensor) circuit. This is an electromagnetic sensor that has 3 wires, which are used for transmission input speed control. It is located near the back of the transmission input shaft and is threaded directly into the transmission housing.
Taking into account that the input shaft of the transmission has slots, the electromagnetic circuit is completed when the castor wheel is near the end of the sensor. When the slots pass through the sensor, the circuit is interrupted and an electronic pattern is formed. This information is sent to the Powertrain Control Module which interprets the electronic pattern as the input speed of the transmission.
The input speed of the transmission is compared to the engine RPM, the percentage of engine load, the output speed of the transmission and the speed of the vehicle, to determine the RPM of the expected input speed. If the actual input speed does not match the expected input speed, DTC code P0715 OBDII is stored.