I guess the guy at Chrysler never heard of an Ultragauge. (Or he just wanted to get you off the phone.)

I can unplug my EGR valve which will set a P0401 in several miles. Then plug it back in and use the Ultragauge to turn the light off and reset the P0401.

I do it when I go to the Dragon or drive the curves on Blood mountain. (I have a switch on the console to unplug the EGR valve.)

Go order an Ultragauge for $80, you will not only have fun learning about the car, but you will also have a powerful diagnostic tool and you will have 53 gauges (most of which you don't have now) that tell you all sorts of stuff the PTCM is watching. You can read the codes (in fact, they pop up automatically) and reset them and the light when you get the problem fixed. Or when you THINK it is fixed, you can reset the code and turn the light off, if the problem is still there, it will come back.