Last fall my EGR cooler failed so I had it deleted and replaced the oil cooler as well. I bought a CTS a few weeks ago and I have persistent DTC codes P0403, P0404 and P1000. Ive read not to worry about the P1000 and I know the P0403 and 0404 are EGR related so are they there because of the EGR delete?
I had one other code for under boost, P0299, last week but after reading here the likely cause was sticky vanes I started driving the dog pi$$ out of it. After a few LONG DEEP rolls into the trottle, she actually seems a bit more responsive and not so laggy at highway speeds. The most boost I have seen in my WOT runs has been 28 psi and I also monitor the VGT duty cycle and it moves from 15% to 85%, 15% getting into it and usually anywhere from 50% to 85% while at highway speeds. There doesnt seem to be much rhyme or reason to the VGT when cruising

. Anyway I cleared the P0299 code and its gone for now. If it comes back Ill guess Ill start thinking about having the turbo cleaned. In the mean time I plan on following so many of ya'lls advice...drive it like I stole it.