I had the same 0234-issue on my 2010 Opel Insignia 2.0 Turbo with the A20NHT engine ( also called LDK) , similar as in 2011 Buick Regal cxl. I solved it by increasing the Allowed Overboost Error somewhat.
See also thread:
https://www.hptuners.com/forum/showt...-A20NHT-26-psi