I checked my codes today and p0401 came up. (engine light is not on) I googled it and it looks like it is insufficient egr flow or something down that line. Heres the deal; the truck has been tuned with the egr turned off and had a blocker plate for about 35k miles and this is the first time i noticed the code. Could have been on for a month or two already buts that it. If the egr is still turned off this code shouldnt show, correct? Thanks!