You are about the fourth or fifth person to have this problem (intermittent error code 22) in the last year. It happened to me about three or four years ago.
It is either coincidence that when you changed your oil it happened, or you knocked a wire/disturbed a connection to the Kev mod or AIT sensor when you did it. Every time this problem has raised its head, it has been down to a loose connection where the Kev mod is tapped into the AIT sensor's wiring.
Read this thread...
http://www.xt660.com/showthread.php?t=24104