Ok.... So I bought a 2012 6.7, G56, 4WD with 64K miles. Bought it from a used dealer out of Texas and shipped it back to me in GA. It was communicated to have been fully deleted and tuned with EFI Live. (No info as far as 1 or 5 tunes or what tune/tunes it was supposed to be)

So I get it, and things do not add up. It does have a "5 position" switch in the cab that is supposed to be used for switching between tunes. There is not an aftermarket display to show engine parameters, but there is an EGT and Boost gauge on A pillar. These were actually not working when I received the truck, I have since found and resolved the power wiring that was purposely disconnected behind the center dash area. So I now have a way to monitor EGT and Boost. The "5 position" switch confuses me, because I followed the wiring (3 wires) from the back of the switch to a connector at the top rear drivers side of the valve cover. I thought this was supposed to go onto the OBD II port. Less than 60 miles on the clock since I got it, and check engine light came on. I grabbed my handy code reader, codes are P040D and P051B. P040D is EGR related and P051B is for Crankcase Pressure. In addition, the "5 position" switch does not make any change in the truck's performance no matter what position it is in.

Here are my questions:
1. Is the "5 position" switch supposed to be connected to this connector in the engine bay?
2. The current MIL codes (P040D & P051B), am I right in thinking these should not exist if it has been tuned for the delete?
3. Anyone know of a shop in GA that is well versed in EFI Live for 6.7 cummins?
4. Minimum.... would a new single EFI Live tune installed ontop of what ever is in my truck solve the Check Engine codes?
5. Better....can a different tuner (MM3, EZ Lynk, Mini Maxx) be installed over the existing tune without consequences of incompatibility?

Any and All help is appreciated.
Thanks,
Chad