Turn ignition on or start the car.
While holding the "options" button down, press the "fuel" button 4 times quickly. This will start a scrolling list of all modules, and the number of codes contained within each module.
From here, enter the manual diagnostics mode by pressing any button other than "e/m", this will display the individual codes contained within each module, use "options" button to scroll forward, the "trip" button to go back to view each code.
You are looking for the code in the first module (10-PCM - code likely to be P0440 or P0442). To reset this, and any other code stored, press and hold "reset" for a second or so until it clears. When all are cleared, you will see the message "no codes" displayed.
When done clearing any/all codes, press the "e/m" button to exit disagnostics and resume normal DIC display. Your check engine light should be out at this point.
