I recently had the egr code P0403 come up, 38 months old and 48,500 miles.

Dealer said it was the EGR ports clogged up and needed cleaning, and it wasn't covered under the emissions warranty. Gave up arguing with them over what my emissions warranty booklet says.

Called customer service and I thought I was talking to Dell tech support.

After getting no where with two people there I called the dealer back and requested to see a factory rep - with that the dealer offered to repair my truck.

They repair sheet says "EGR Dirty" J6353 Module PCM Transmission re-programming.

Also cleaned EGR per bulletin 06-06-04-066D.

The truck seems to have have a flat spot now when accelerating after a steady cruise and according the MPG computer my mileage has dropped about 3 mpg on the highway, only averaging about 14.5 at 65 now. Use to get about 17-18.

Does this code throw a "limp or maintneace mode" into the PCM?

Any other thoughts?

I was planning on doing a variety of things to the truck now that it is almost out of "phase two warranty" (36-36,000, 5-50,000, #3 5-100,000)

Thanks

Mine threw the P0403 a few months back. The stealer cleaned it twice, and the third time after calling the GM District Manager they finally decided to replace it. I can't think of anyone that had one cleaned that didn't throw another P0403 within 1,000 miles.
The EGR is an Emission Device, ask the Feds, and the stealer should have covered it under warranty.
I didn't have any flat spots the times they cleaned it, and it doesn't go into limp mode either. When mine is out of warranty I will probably block and stick it.

Yeah, I had the same problem, and all was covered under warranty. I think you should have a "talk" with that dealer.