I've had an ongoing issue that has my GM XLR-Certified Master Technician mystified. I have an 05 XLR 30K miles that randomly displays the "Service Engine Soon" light in the DIC when I start it. This weekend it came on and I went directly to the dealership, message displaying in the dash. trouble is there are no codes whatsoever in any of the computers. I was told that for a message to display a code needs to activate it, but not in this car... This has been continually happening for several months, but no codes. Has anybody seen this before, or are there any ideas? My tech is stumped.