I have been having trouble with the EGR codes for a couple of years. I finally broke down and installed a new EGR valve and cleared the codes. They quickly returned. A few weeks later, for completely different reasons, I added 1 quart of Marvel Mystery Oil (MMO)to the engine. The engine has been running much smoother, my gas mileage has gone up from 12.5 mpg to 15 mpg and......the engine codes have all cleared. No codes for about a week now. Crossing my fingers. Still burning/losing oil. I plan to let the MMO sit in the cylinders for a couple of days, next time I have a weekend while I won't need to drive the VX.