DTC P0715: Input/Turbine Speed Sensor Malfunction: Description
WARNING: This page is about a different car, the 2002 Mazda 626 and 2001 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
DTC will set if vehicle speed is 25 MPH and input/turbine speed sensor signal is not input to PCM for one second or more.