A sign of a radio with coding is the presence of a red symbol in the form of a key on the front cover. If the red LED on the front side flashes when the ignition key is removed, this means that the coding is activated and the radio is ready for operation.
The code prevents unauthorized switching on of the radio receiver if its power supply has been interrupted. The radio receiver power supply is interrupted, for example, when it is removed, disconnected from the battery, or when the fuse burns out.
If the radio is coded, it is necessary to set the radio code before disconnecting the battery or removing the radio. If the code is unknown, only an AUDI service station can turn on the radio.
The individual code number is given in the radio operating manual. It should not be stored in the car.
Removal the electronic lock
1. Turn on the power, turn on the radio.
2. Press the "FM" and "DX" keys simultaneously until the display shows "CODE". Release the keys, and the display will automatically show "1000" shortly after.
Warning: For the "chorus" and "concert" radio receivers, the "TP" and "RDS" keys are pressed instead of the "FM" and "DX" keys.
3. Using the station selection keys 1 through 4, enter the secret code. Key 1 enters the first place of the code number, key 2 the second place, etc. Press the key the number of times corresponding to the code digit.
4. Then press the "FM" and "DX" keys simultaneously again until the message "SAFE" appears. Release the keys. The radio is now ready for operation again. The frequency is automatically displayed.
Warning: If an incorrect code is entered by mistake, the message "SAFE" first flashes and then lights up continuously. Now the entire entry process can be repeated again. If an incorrect code is entered again, the radio is blocked for approximately 1 hour. After 1 hour - the radio must remain switched on - the blocking is removed. The entry cycle is repeated for subsequent attempts.
Cars produced since 8/98, equipped with "beta" and "gamma" radios
After connecting the radio to the power source, automatic data exchange occurs between the radio and the instrument panel unit. In this case, the code recorded during the first activation of theft protection is compared. If the code matches, the radio is ready for use.
The radio receiver is blocked if it is installed in another car or if the instrument panel unit is replaced. In this case, you must remove the blocking by entering a code.
(A link to the original source is available on the website: AUDIMANUAL)