I when to Autozone to clear a code. I don't think they know what they doing. One guy said to turn the engine off then erased the code and the other guy said no leave the engine on...the engine was on ... and he was unable to clear the code.
What is the correct way ? Engine on or off ? Thanks.

 

you dont really need the engine on. jsut key on. then after you clear the code then you turn it off. the scan too usually tells you what to do...

 

Most generic scan tools need to have the key on, engine off to clear a DTC.

 

you need to have at least the contact on.