I have 2005 GMC Dmax/ALLi. Installed Magnaflow CAT back exaust and S&B cold air Intake system. Check engine light comes on and I get codes P0401 and P0404. Exaust gas recirculation insuff and something. Is there something that can be done to correct this problem easily. Can clear codes and they may not return for a week, sometimes they return in a few days. Is it dangerous to drive if getting these codes?