My 2004 xc90 check engine light is coming on and the code is 6804. Turbo and says pressure too high. I read many things on here and here is the history of the vehicle: About two months ago, I replaced the turbo as there was TONS of blue smoke coming out. So my mechanic replaced the turbo and this code continued to come up; initially he thought it was because there was remnants of oil or the sensors were not clean. I then read the posts here, which said to replace the boost control solenoid, which he did- as well as thoroughly cleaned sensors and changed any hoses with wear and tear and insured the connections are all tight and secure. I could tell the difference in the car but after three or four days, the engine light came on. It feels like the transmission is not shifting to the lower gear at 2500-3000 rpm. I was getting on a freeway and trying to gain speed and it wouldn't switch gears; and then it did eventually. Also, I feel it is sort of hiccupping as I go up the hill to my home. Again, it will stay in a lower gear and then a bit of hesitation. Any help would be greatly appreciated. As you can imagine, in the last 2 months I have spent $2500 on trying to fix this problem. It just feels like it is not as safe as it once was. Thank you.