So after a few days and more than 160 miles driven, still no sign of CEL and my code scanner doesn't show any pending codes. I guess that new air temp sensor fixed it and the dealership tried to rip me off on the EGR valve replacement? Hmm...

When I plug the code scanner in, the green light on the scanner comes on. But when I press the start/stop button, it switches to the yellow light with the EGR, Particle filter, and one of the N-something monitors blinking. The manual for the scanner says these monitors run once per trip. I did a bunch of various types of driving in that 160 miles so all the testing should have been completed. I only used this scanner once before so I'm not really sure if this is normal or not.