today a friend and i tried to swap out the stock cat to install a carsound cat from ipsracing..we unplugged and switch the two 02 sensors and eveyrhint but it turns out it didnt fit..so then we swaped the stock back on and next thing you know check engine light came on when we started the car..i know for sure it has to do with the 02 sensor bc it was touched and taken out ..so then we unplugged the negative terminal of the battery to reset everything and the light was gone..do i have anything to worry about since the light seems to be gone now?..if there was still a problem it would come back right?..thanks

 

Yeah, if there's a real problem it'll come back. Then you can read the code...