tech ? non mopar

After replacing the fuel filter, test the pressure again.

I had the same codes on my 03 Denali and found a forum that discussed this problem as a defective intake gasket. They said that GM re-engineered the gasket and offered for sale thru the parts Dept. the revised gasket is a different color than the original, so they can't be confused with each other. The leak is supposedly on the inside of the engine in the lifter valley, so traditional leak tests don't work.

My codes only appeared on freezing cold days, so if reset during summer, they were fine all summer long. I tried a simple fix, used Lucas rear main seal fixer additive in my oil and have never had the problem again.

Good luck!