I can't remember exactly how but i know it can be done...
you use your key and gas pedal while the car is not running to do it.
I remember it is SOMETHING like...
turn key to accesory position.
wait 3 seconds step on gas 5 times in 10 seconds wait 10 seconds step on gas until check engine light starts blinking the code (it will flash 10 times for 0, and you get 4 digits)
To clear, after flashing is over, hold gas for 10 seconds.
If you can get it to flash the codes, you can clear it!