there is a connector just in front of the battery in the engine compartment. there is a black button and a red led light to check for codes. is the check engine light on? if so with the key in position 2. key on engine off press the black button for 3 seconds and then see how many times the light blinks. this will indicate what code you have. you may have more than one. after that you will have to look up the code and do some testing. hope this helps