A few weeks ago my 07 S60 2.5T started bogging down when I would wait at stop lights. After a couple days my CEL finally came on and after a stop at Autozone the code pulled was P2188. Research pointed to many possibilities to include PCV Sys, O2 sensors, MAF sensor and a few other expensive repairs. I took a shot and went with both FWD/AFT O2s (Bosch OEM) and I also picked up a fuel filter for good measure since my car has 103K. I changed the O2s and the car drove great and many of the hesitations my car had been having mostly went away. The next day the code cleared itself and the CEL went out. However, my victory was short lived and the CEL returned and the bogging at stops also came back. I stopped at Advance Auto this time and the code pulled this time was P0101. I decided I needed to change the fuel filter which I was unable to replace a few days earlier. I changed the filter after work and put the car in the garage the next day when I was driving to work the car performed awesome and the CEL once again went out. Again this was short lived and the CEL returned in a couple days and I had about enough. I took the car to the dealer and when I told the service manager what codes I had, he told me the codes they get out of their diagnostic machine are different and they don't correlate to the P-codes. I thought this to be odd and awaited the results of their troubleshooting. I was told the #5 coil pack was bad and the plug had been fouled out. The dealer replaced the coil and all 5 plugs and $340 later my car drives awesome, the power has returned. So this leads me to believe that the cheaper handheld OBD II testers are not able to accurately troubleshoot your car and Volvo has a little propriety in their system contributing to all the false troubleshooting actions I read about in all the blogs concerning these codes. I hope this helps others that may be experiencing these same symptoms. If your car has around 100K consider changing the plugs and most likely a coil pack or more.