After my check engine light came on, I tried reading the error codes with a cheap Harbor Freight Autel code reader. The "codes" were $7EA and $7E8, which are not in the correct format. Google turned up similar "codes" for a variety of GM cars. Someone claimed it was associated with a bad cat. My G8 has 4689 miles and has spent an abnormal amount of time idling in the driveway. I use premium non-ethanol gas. Any ideas?
2009 G8 GT, premium, sport, sport red metallic
MagnaFlow 16887 Street Series cat-back
Superchips Cortex: Rotofab 91 Octane, 25% TM, AFM off
and splash guards (that look better than dirt)