First off, the person who said you over revved your engine to 22K is breathing their own exhaust fumes. Not possible!

On the check engine light. I had the same problem with it suddenly showing up. It turned out to be the gas cap. It had not been fully tightened. (this has been mentioned before by several others)

If that isn't it, it probably has something to do with the smog system. But check the gas cap first.