In IL they require emissions testing every other year for cars 4yrs. and older. What's bogus is that most state testing facilities got closed down and redirected to private mechanic shops. Which of course makes me weary that they will try and force some sort of repair on me. Very few state run places are still open. They do the OBD check for newer cars. You're allowed for one system failure and thats it. For me it's the EVAP code that I can't shake. I think it's 7 systems total that they check. Hate getting that notice in the mail. My GTP is due for a check since October. Can't renew my plate sticker till that gets done.