Electrical issues
 

How much does it cost to update the software on a 2002 Volvo S80 2.9L?

Depends on the software. I checked with the dealer yesterday to update the software on my CEM to activate fog lights. They said $64 for software and $89 labor (1 hour) plus tax. Some programming might take longer. When you call them, have your VIN ready. They'll need that to determine what software you need.

The fog light software is not an update. A CEM update is a different piece of software. Of course, there are updates for most modules. Most updates don't fix anything. The TCM being the exception.