It's probably just stuck on due to not being used much (I'm guessing?). I'd try soaking the seal with some penetrating oil or something for a while and then see if you can gently twist and break it free. I'm not familiar with 2001+ models, but if it's anything like the older ones, the danger is that...

If you are having a hard time reaching it, remove the cold air snorkel first. Then man up and pull it outta there!

It is held in with a rubber seal. You pop it out, not lift it out ... catch the drift?

MDK here...so, they all get stuck. Just twist, carefully, left and right till it breaks the seal. It has an o ring that dries out. Pita..why, when we pay 30,. 40,50,000$ for a Volvo we can't have a METAL DIPSTICK!!!