How do you unlock your peugeot 306 radio with error 4 showing?

Follow these steps to unlock your Peugeot 306 radio that displays the error code "4":

1. Turn on the ignition of your Peugeot 306.

2. Press and hold the "1" and "6" buttons on the radio simultaneously.

3. While still holding the "1" and "6" buttons, press the "3" button.

4. Release all three buttons.

5. The display on the radio should now show "0000".

6. Use the preset buttons on the radio to enter the four-digit code that is unique to your radio.

7. Press and hold the "6" button to confirm your code.

8. The display on the radio should now show "CODE".

9. Press the "1" button to turn on the radio.