2008 2.0lt GT legacy. I was getting occasional very hard shifts under hard acceleration and on inclines, sometimes with flashing transmission temp, ABS light and traction control light. The fault decode was P1710, “turbine speed 2 sensor”. 99.9% of the time the car drove very smoothly.
Research on forums and other online info I was able to determine the fault. The sensor is a HALL effect transducer incorporating a transistor and from experience transistors do not like getting hot. Given that these symptoms were occurring under hard acceleration and on inclines I deduced that the sensor was being overheated by transmission oil, reducing the oil level seemed to stop the fault codes but hard shifting still occurred.
Subaru’s Fix was a new valve body at $3300. This is a known fault and Subaru has subsequently modified the valve body.
I removed the valve body, detached the sensor as seen in below photo.
I then purchased a generic Hall effect 12mm sensor SENSPD500 from MSEL in Marua road, Pamure. I mounted it at the same height and position as the original sensor as per the photo below. To date, 3 months in, the car drives sweet, no hard shifts, no fault codes.