If you have computer trouble codes P0014 , P0016 , p0017 for camshaft / crankshaft correlation, most likely the sensor should be replaced.You may have 2 of these on your Volvo. One for the intake camshaft one for the exhaust camshaft.Please order 2 if you have both. The replacement procedure is simple.The camshaft position sensor installed into the housing and is mounted onto the cylinder head. Attached to the housing with 10 mm head bolt.

This device should be replaced if you have have to run the starter for long time before the engine starts.
The sensor have plastic housing and long exposure to heat and vibration can case internal damages , not visible from the outside. Also , the sensor can be fully functional when the engine is cold. The trouble comes , when you are attempting to restart the engine after it had reached operating temperature. Conventional scanned will not show failure of the sensor , but it can be identified by Volvo specific scanned or compatible scanner with live data features.
This item is original Volvo part. Made in Japan by Denso, It is marked with VOLVO brand and manufacturers numbers .
This camshaft sensor will fit many models,. below is the list of the vehicles that is using the sensor:

2002-2004 C70
2002-2009 S60
2002-2004 S80 2.9
2002-2005 S80 T6
2004-2005 S80 2.5T
2004-2005 S80 2.5T AWD
2005-2005 S80 T6 Premier
2006-2006 S80
2002-2007 V70
2003-2007 XC70
2003-2004 XC90
2005-2005 XC90 T6
2005-2005 XC90 V8
2005-2006 XC90 2.5T