I have a 2000 S40. Two days ago the "check engine" light came on with a "flashing arrow" next to it. According the the manual, this indicates a transmission fault. I noticed that the transmission would not drop to low gear. I had to manually shift to "low" when starting and then shift to drive. The transmission would shift through the remaining gears as normal. I would have to repeat this procedure each time I stopped. The next morning the "arrow" was not on (or flashing) and the transmission was shifting through all gears normally. The "check engine" light remained on. I went to VOLVO for a check. I was told that the "Gear Positioning Sensor" was the cause and it would cost $500. to replace. Since the "arrow" is not flashing and the transmission is shifting normally, could it have been an electrical "glitch" that caused the original problem? The dealer would not extinguish the check engine light. The transmission is still shifting normal. Any ideas? Could I replace the Gear Positioning Sensor if I really need it?

I wouldn't worry about it, most times when these cars have glitches like that you just need to shut it off wait a few seconds and start it back up.