This requires a special test drive to reset all the readiness monitors. I would call around to the Volvo Dealers and some shops that specialize in Volvos and/or emissions testing, and have them perform this test drive for you.
Here is all the info you need, but it's fairly technical, so if you have any problems, I strongly suggest you have a shop perform this. Good Luck. http://repairpal.com/drive-cycle-emissions-readiness http://repairpal.com/Drive-Cycle-Issues http://repairpal.com/drive-cycle-how-to-perform-a-basic-drive-cycle