I recently changed the thermostat and sensor on my 2002 S80 T6. Whether you are changing the timing belt or thermostat (to include thermostat, thermostat housing, and/or sensor) you will run into a sometimes nasty problem with the timing belt cover related to the hose connecting to the plastic elbow on top of the thermostat. I wanted to share my experience in hopes of helping someone else who might benefit. I will caveat all this to state that I'm not a professional mechanic; just a guy who loves his (getting older) S80 and likes doing as much of the required maintenance himself. Here's the link I created. Hope it helps.
https://ucn5pg-dm2306.files.1drv.com...ver.pdf?psid=1