Multiple codes came out of nowhere.

The C5 Corvette I bought in 98 was my first truly computerized car. I was driving it one night and when I drove across some railroad tracks, the dashboard lit up like a Christmas Tree and the car went in to limp-home mode. Drove it a couple of miles like that (had about 15 to go to get home) and decided I didn't want to drive it the rest of the way home like that. But I'm a computer guy. I figured the problem might be some kind of bug in the software. I pulled over and shut the car down, waited a minute or two, and restarted it. But it was still in limp-home mode. But GM in its infinite wisdom had designed the DIC so you could go in to diagnostic mode to read out and most importantly, clear any trouble codes (individually or all of them at once). So I put the DIC in diagnostic mode and cleared out all the codes. Shut the car down, restarted, no trouble lights, drove it home and then continued to drive it for a few more years and never had the problem again. But I did take it down to the dealership (where I was friends with the service manager) and had them pull and reseat every computer module plug in the car.