Engine Over Boost 2004 XC90
 

Check Engine Light is on. Had it checked with hand held computer at Parts Store. It said Engine Overboost. What is that. Please help. Wife is upset. We just bought her the care a week ago.

I am having the same problem with my 03 XC90. Everything is fine for driving under 3000 RPM. But if I get over that, the turbo goes into safe mode and barely moves the car. I get the P0234 CEL code and if I clear it, turbo is back in action. I had 2 P0234 codes so I replaced the TCV, the one right next to the air box. Then, when I "overboosted" and the CEL came back on, there was now just one P0234 code. So I ordered the other boost control sensor at the lower inlet of the intercooler in hopes that this will clear everything up. But after a few days of research it may also be the waste gate. Anyone have any imput on this? I dont have any other problems with it besides the overboost (at the moment).