please help anybody- i have a 96 honda civic ex...my check engine light has been on for a while ...when i took the car to the emissions place it failed because the 02 sensor...i have a full-catback exhaust? will i have any problem buying a new one and changing it? does anyone know where it's located and how to change it??? is there a good place to buy them at??? PLEASE HELP I CAN'T REGISTER MY CAR UNTILL IT PASSES THE EMISSIONS AND I ALREADY HAVE A TICKET MUST CHANGE ASAP.