For the record, on Saturday I got the P0740. Ironically, I had just stopped by the dealer and picked up my transmission fluid, as I was planning to do my drain/refill that day. The light came on as I was accelerating up to ~50mph, which is right where the the converter locks in 4th. After the light was on, I noticed that I could no longer get a solid lock in 4th. Other than that, the trans worked fine. Anyway, I came home and did the drain/refill and cleared the code. Since then everything is working fine again, including the 4th gear lock. No CEL light so far. Not sure how long I have - we'll see.