How can I check the codes in my 98 GM. The light came on tonight . I was starting it and let the key off to quickly then it came on when I started it after.

Autozone reportedly will scan it for free. you can buy an OBII scanner, EBAY has them last time I looked
or, you can get free software online in a lap top and build/buy an interface and cables.

Thanks. I will hit Autozone in the AM.

Joey autozone scan only gives codes, which is all you need for now I guess, be on look out on ebay for Snap On MT-2500 with a 98+ cartridge It's what I use, almost as good as a T-2 but it does have limitations.

Thanks. I will try e bay today and see what comes up. I will ask the snap on guy monday as well. He does trades towards new ones and must have some old ones around.

Code cleared next time I started it.

MIL light went off, the code is still stored in the PCM.
It is best to know what it is.