Hello all - this morning about 30 mins or so into my drive to work, going pretty fast on highway, I noticed my CEL started blinking slowly. It would do about 11 slow blinks, then do nothing. It did this maybe 2 or 3 times, and then stopped / has not done anything since. Engine temp seemed normal, oil pressure seems normal to me, I re-did the gas cap after getting to work (I did get gas yesterday, but at the same place I always get it). The alternator was replaced about 2 weeks ago under warranty by the dealership. What's strange to me, is that I drove it to Autozone (by now the light had long been off), and used their tester tool, only to get nothing / no code.....isn't the code supposed to be stored into the computer?

Anyone have any input here?

 

yup, it should have stored something.
Post your year/model/engine/miles please.

 

2016 Silverado LT 5.3L 67xxx miles

 

Some OBDII scanners list active, stored, and permanent codes separately. Make sure you check all lists.