Yesterday I ran into an issue with my SL1. The charging system warning light came on as I was running some errands. At first I thought I had a serpentine belt issue. I stopped to check the belt. It was fine and nothing else happened to indicate an issue with it. I decided that since I only had one more stop close to home, I would run that errand. The car started up just as normal after the stop. But as I left the parking lot the SES light went on. The car also would not shift out of first gear. I limped home slowly and checked for the codes. I read the three codes, P0300, P0420, and P0452. The P0420 code is familiar to me (and probably every other S-series owner). What I can't figure out what the other two codes have to do with the transmission issue. Any help is appreciated.