Welcome to the forum !
Even though the P0501 code is not listed in the service manual, after a Google search I would hazard a pretty good guess that the transmission conductor plate is the culprit.
There are lots of videos on uTube about replacing this, just search for 722.6 conductor.
( It's a somewhat messy job, but the average DIY'er can do it.
I'd say about a 6 on a 1-10 scale of difficulty.

http://www.ebay.com/itm/722-6-Transm...hVe8rc&vxp=mtr

and

http://www.ebay.com/itm/Pentosin-108...YAAOSwCU1Y00hV

and