As noted by others, the check engine light has to be manually cleared.

Removing the negative battery cable is the quickest and surest way to clear the check engine light, but if you have your original anti-theft radio, you are going to need the radio code if you disconnect the battery.

If you clear it using the button, plan on holding the button down a lot longer than the book says. Takes around 15 seconds on my '91. I should remember the exact procedure but I don't. Hopefully someone else will, or I will bring in the book tomorrow.