i have done this before and have searched for it but i can not find out how to do this. how do i pull codes without a reader, as in using the ignition and using the blinking (check engine light i beliver) to tell the codes. i've done it before i just cant remember how. it involves switching the car on and off a couple times

 

That technique does not work on OBD2 cars. You'll need a code reader.

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