code 3

Hello all, I just bought a 2001 Beetle. Nice car, but I can't get the radio to work. It always says CODE 3 when I turn on the car. If I press a button the numbers change. Pressing 2 will make it say CODE 3 2. Pressing 1 would make it say CODE 3 1 etc. I think it used to say CODE 1 and CODE...