2013 CTS coupe proximity sensor mystery
 

The other night I locked up the car for the evening. In retrospect I recall she didn't chirp back at me indicating all was locked. The next day I went out start and couldn't get in. Thinking the key fob battery was the problem i replaced so the proximity sensor would work but nothing. Got in through the secret trunk method but everything was absolutely dead. The car battery has given NO indication of problems but out of desperation I decided to jump the car. Shockingly she started right up after the theft deterrent light on the dash settled down. Before the theft deterrent light went out it would just crank but not start like there was no fuel (probably how the theft deterrent works?) Disconnected jumper cables and it easily started again (evidently no battery problem so I have no idea why jumping let it start.) BUT, Immediately I noticed the CEL was on. Turned out it was reading fuel related codes. I noticed the remote start wouldn't work either but i believe that is disabled whenever the CEL is activated? I made an appt. to have it looked at and when i went out to start a few day later … no problem & the CEL had gone out?!? Car runs great / no CEL / no problems but I'm leery that this might happen again at a more inconvenient place than my garage. Can anyone help me understand what the heck was going on? THANKS