I has a SES light on yesterday, and finally got around to checking it out this morning. When I hooked it up and pulled the code, it said Exhaust Gas next to the code. Besides the obvious meaning to the name, what exactly is this? Bad gas or something?

Exhaust gas recirculation, maybe?

PO401 EGR System Flow Insufficient
PO403 EGR Solenoid Control Circuit
PO404 EGR System Performance
PO405 EGR Pintle Position Circuit Low Voltage

Hmm, like a dumbass I didnt write down the code, and just erased it. I dont think it was anything important, it happend when i was going 30mph, and i didnt see any change in the behavior of the car. I was just curious about the name

well if it pops up again.....WRITE DOWN THE CODE

Ok, I got it again, the code was P0401 what should I do about this?

bad EGR?

Yea, thats what I understand from bill'* posting. Egr, eeh? :?

GMParsdirect is telling me that Emission Control System Hardware (Valve) is going to cost me 98.00$ and 20.00$ for shipping. Is this the piece I need, or can I do something on my own?

http://www.gmpartsdirect.com/partsvoice/frameset.cfm

Try buying a new gasket, pulling off the EGR......Spray and scrub the living daylights out of it the best you can with a tooth brush or something and a really strong solvent cleaner., and then re-install t and see if the code comes back?

Allright, next question is, where is this device and what tools are required?