My 05 500 had a CEL. The code was for the EGR valve. Before I was able to change it the car went into fail safe mode. I changed the EGR yesterday and the car ran great. got in it this morning and started it up and it went right back to fail safe mode. Assuming that I didn't miss hooking up a vacuum line or connector, does anyone have any suggestions on where to start?

 

Did you try disconnecting the battery and touch the pos and neg cables together to cancel the code?