ust found a great solution on another website for my 1997 Peugeot 306 and it worked!
The label on the radio states
C6CBK0094099
C70000003214
Take the 3214
Add 1 to the first digit (1+3) = 4
Add 2 to the second digit (2+2) = 4
Add 3 to the third digit (3+1) = 4
Add 4 to the fourth digit (4+4) = 8
As you can only enter numbers 1 to 6 on the radio, for any numbers greater than 6, subtract 6 therefore the code to enter is 4442
.........
.....THIS WORKED FOR ME CHAPS, ALL UP AND RUNNING, STEREO WAS CLARION IN A 98 306
BUZZERD
July 2010