I keep getting codes P0401 Exhaust Gas Recirculation Flow Insufficient Detected ,and P1409 EGR vac system leak,. The truck runs great no smoke and lots of power.
But what do I do to fix whatever is causing these codes.

97 GM 6.5 Automatic, 4X4 1/2 ton pickup

Pete.

 

Check vac line routing and look for cracked/broken vacuum lines from each vac solenoid to its next connection.

 

I have done this and can't find any broken or cracked lines. New vac pump , and good vac at all locations too. I am getting the same codes on both trucks, a 97 and a 98 6.5.

 

Then you need to check the wiring to the vac solenoids and maybe replace the solenoids?