How much is it to get codes read and cleared at Autozone?

generally free my favorite number... you must have an ODB2 computer though

OBD2 only and they dont charge. At least they shouldnt.

Definatly free. I've gone there several times (cuz I didn't know about the whole gas cap turning 3 times thing.) They can tell you the code and clear it, but a lot of the time they have no clue what the code means.

Do what????? What do you mean turn the gas cap 3 times? I just turn it until it clicks a few times..

With mine, if I turn it much more than 3 times after it clicks (or don't turn it until it clicks at all) it will throw a check engine code. If the cap is too tight, or not tight enough, the amout of vaccuum will be wrong. I think this is only on OBD II cars though.