Check out the following forum link, you should be using the genuine Subaru fluid that is specified for your transmission type (there are multiple types depending on your transmission model).
www.subaruoutback.org
Once you are using the correct fluid you can then monitor the transmission fluid pressure to see if it is within specifications.
Seagrass
P0841 Secondary Oil Pressure Sensor Performance
DTC P0841 SECONDARY OIL PRESSURE SENSOR PERFORMANCE DTC DETECTING CONDITION: ^ Control valve hydraulic circuit malfunction ^ Secondary pressure sensor fault or characteristics malfunction TROUBLE SYMPTOM: ^ Acceleration is poor during standing start. ^ Shift control malfunction ^…
www.subaruoutback.org
