Recently my wife's S80 has recently had a number of computer error messages including: STS Service Required, Transmission Service Required, Power Steering Service Required, and (of most concern) Brake Failure. The messages tend to start flashing after driving 10-15 miles and occur virtually simultaneously. The (non-Volvo) service shop was able to reset the messages and verified there were no problems in the components, but after driving a few miles the messages came right back. Is this something I should be concerned about or should I just accept this as a quirk of the car? Any ideas on fixes?

I have the same problem and the dealer claimed "an internal fault" of the ABS Module, $860 so I'm trading it in on another brand. Volvo used to be a reliable car, but after a lot of annoying and expensive repairs I had enough. Good luck!

You need a new ABS control unit.

So the ABS control panel would impact all of these systems or cause multiple incorrect error codes?

Thanks.

Most likely. All those ECUs get vehicle speed signals from the ABS control unit and when that unit "goes south", the other ECUs see errors. It's becoming common in S80s now.

I'd advise taking the car to a dealer.