hello all, wondering if any of you know what code 12 is just did a complete tune up on my 97 dakota ( plugs cap rotor wires pcv air filter along with oil change ) , idles iratic or up and down bows black smoke as well when reved up, read the codes and code 12 appears but checked with obd11 scanner and read something else erased that one but still get code 12 on dash but check engine is not on, also just bought the truck was doing same but worse when i got it runs better now but?????

 

12 is a OBD1 code. But it stands for "Battery was disconnected within the last 50 key cycles."

This is perfectly normal. Don't worry about it.