http://www.techshopmag.com/issue/art...ontentid=96306
http://www.1addicts.com/forums/showthread.php?t=207508
This is what I could find for it. It does not give a range of build dates, and I don't see a change in part no. on realOEM.
If it were me though, I would definitely try pulling the codes when you get them, and see if its the intake or exhaust side you are getting an error on. Then try cleaning the solenoids with electrical parts cleaner, and swapping the solenoids between intake and exhaust sides. If the code pops up again on you, and follows the solenoid, then you know that one is bad and replace. If it still is appearing at the same side, even after swapping, then it probably is bearing ledge related.