Ignore whether or not the light is on, the knock sensor code won't turn the light on!

Get the codes pulled. If you're not willing to go to autozone or some other place and get them pulled for free, then there's nothing else to do because you're not willing to do anything yourself.

I don't mean to be a dick, but if you're going to ignore what others know, it's going to be difficult to learn what to do. At that point, just take it to the dealer and have them look at it. They'll be happy to charge you.