Just bought the truck not ever 2 miles up the road it through the code PO6DD, 5.3L 120K on it, oil pressure seems normal compared to what I have read, 40 psi cruising 60 when giving it gas, and 30 when at idle, What are some possible problems and where should I start?

 

First step is to change the oil and filter with the correct oil and a quality filter. This code refers to the dual stage oil pump.Since you just bought the truck, you don't know how long the oil and filter have been in the truck.