In regard to another thread, I found that there was a change in the design of the accelerator pedal assembly around MY2006.
Prior to the change, the accelerator pedal used variable resistors (potentiometers) that varied with the position of the pedal. For 2006+, instead of variable resistors, Hall effect IC's are used.
Variable resistors depend on metal contacts that slide on a length of resistance material. The moving contact can wear, and become contaminated/corroded. This could lead to incorrect signals, and the trouble code. The Hall effect system doesn't depend on moving electrical contacts -- instead it uses magnetic fields, which should be far more reliable.
opposedforces.com lists two p/n depending on date of production, for all 2.5 Legacy (Outback) from 05 through 08. 36010AG021 appears to be the earlier version, and 36010AG140 is for later production.
I wonder if the replacements being supplied for defective pre-change pedals now use the newer Hall versions . . . .