I have a 2003 TL-S with nav. I had the battery replaced twice. First time mechanic did it with the car running so the radio and nav codes would not be lost. Worked fine. Then I decided to put in a different battery and his helper messed up by turning off the car and replacing the battery. The nav still works but the radio displays "error" and he says the radio has to be pulled and something done which I'm not sure of. Since he is not charging me anything to do this and I have been going to him for 6 years, I totally trust him. But I don't want him to do all of the extra work. I tried it myself and the error code just keeps updating now up to error6. I even tried leaving the radio on for 1 hour to no avail. I am the original owner and have the original card with nav and radio codes but they don't work. Is the mechanic correct and this is the only way to fix the radio? I tried your 1, 6 and power depression simultaneously and that did give me the correct S/N on my card. Any quick fixes??