Audi A6 Radio Code — Unlock It Online

An Audi A6 showing a blank radio display or the word SAFE after a battery change is one of the most common scenarios we encounter. The A6 spans four main generations with three different head unit architectures — the Concert/Symphony family, the Concert with MMI controller, and the fully integrated MMI 3G+ system — and the unlock procedure varies meaningfully between them. This guide covers each generation so you can act immediately.

Why Does the Audi A6 Radio Lock?

Audi equips its head units with an anti-theft PIN requirement that activates on every power interruption. Whether you have just replaced a flat battery, had the battery disconnected during a service, or swapped in a replacement unit, the result is the same: the radio will not operate until you enter the correct code. This applies to Concert, Symphony, and most MMI-era units up to and including the C7 generation.

Finding the Serial Number on an Audi A6

The serial format and location depend on the generation:

C5 (1997–2004) — Concert / Symphony: The serial begins with SEZ and is printed on a sticker on the head unit's chassis. Remove the unit with DIN extraction keys (Audi uses the standard 8.5 mm-spaced four-hole pattern). Alternatively, press and hold the FM and RDS buttons simultaneously for two seconds — the serial will scroll across the display on most Concert units.
C6 (2004–2011) — Concert with optional MMI: Serials again start with SEZ or have no prefix on the MMI navigation unit. For Concert variants, use the same button hold method. For MMI, the serial is found in the MMI menu under Setup > System Information.
C7 (2011–2018) — MMI 3G+: Head unit codes are managed through the MMI 3G+ system. Navigate to Car > Service & Checks > Radio Code in the MMI menu to find the unit serial and enter the code.
C8 (2018–2023) — MIB3 / Virtual Cockpit: The C8 generation predominantly uses MIB3 infotainment, which is VIN-paired. These units generally do not require a user-entered PIN; security is handled at the vehicle network level.

With the serial number noted, order your Audi A6 radio code online for fast email delivery.

How to Enter the Code by Generation

C5 Concert / Symphony (buttons 1–4 + seek)

Switch ignition to accessories (position II).
Display shows SAFE.
Press the AM/FM or BAND button once to show four dashes.
Use preset buttons 1, 2, 3, and 4 to enter each digit (each press increments the digit by one).
Press the seek/scan arrow button to confirm.

C6 Concert with MMI controller

Enter the PIN prompt screen.
Use the MMI rotary controller to dial in each digit, or use the preset buttons if the Concert head unit is fitted without full MMI.
Confirm using the MMI controller centre press or the seek button on the Concert unit.

C7 MMI 3G+ (Harman)

The MMI 3G+ typically shows a PIN prompt on the central MMI screen after power loss.
Use the MMI rotary controller to navigate the on-screen keyboard.
Enter the four-digit code and press the controller to confirm.

Generation Reference Table

Generation	Years	Head Unit	Serial Prefix	OEM	Needs Code?
A6 C5	1997–2004	Concert / Symphony	SEZ	Philips	Yes
A6 C6	2004–2011	Concert / MMI	SEZ / —	Philips/Harman	Depends on spec
A6 C7	2011–2018	MMI 3G+	—	Harman	Often no code needed
A6 C8	2018–2023	MIB3 / Virtual Cockpit	—	Harman	VIN-paired, no card code

Troubleshooting

SAFE: Locked state — proceed with code entry as above.
SAFE 1000 / WAIT: After ten wrong attempts the Concert/Symphony initiates a one-hour lockout. Leave the ignition on for the full hour — switching off resets the timer.
The rotary controller is unresponsive on C6 MMI: The MMI module itself may have lost its code separately from the Concert radio. Check the MMI system information screen to confirm which component requires the code.

Frequently Asked Questions

Do I need a code for my C7 A6 MMI 3G+?

Many C7 A6 units manage security via the car's network rather than a traditional user-entered code. If the MMI boots normally after a battery change without requesting a PIN, no code is required. If it does request one, the code is found in the MMI service menu or via Audi dealer software.

What is the difference between the Concert and Symphony in the A6 C5?

The Concert is the standard-fit CD/radio, while the Symphony adds features such as a six-disc in-dash changer or cassette deck depending on the year. Both use the SEZ serial prefix and the same code entry method with preset buttons 1–4 and the seek key to confirm.

Can I use the same code if I swap a Concert unit between two A6s?

No — the code is locked to the individual unit's serial number, not the vehicle. Fitting a Concert from another A6 means you will need the code for that specific unit's serial.

My display shows no characters at all after pressing the buttons — what is wrong?

On the C5 Concert, you must press the AM/FM or BAND button once after the SAFE prompt appears to activate the digit-entry mode. Without this step the preset buttons will not register code entry.

Ready to get your A6 audio back? Retrieve your Audi A6 radio code online — enter the serial and receive the code by email in minutes.