Harman Radio Code Guide

Harman International — the parent company of JBL, Becker, and Harman Kardon — is the dominant premium OEM infotainment supplier to BMW, Mercedes-Benz, and Audi. If your head unit carries a Harman or Harman Kardon badge, or your BMW iDrive, Mercedes Audio/COMAND, or Audi MMI system is asking for a code after a battery change, this guide explains how these systems work and how to restore access.

Which Vehicles Use Harman OEM Infotainment?

• BMW — 1-Serie F20/F21 (2011–2019), 2-Serie F22/F23/F45, 3-Serie F30/F31 (2011–2019), 4-Serie F32/F36, 5-Serie F10/F11 (2009–2017), X1 F48, 5-Serie G30 — iDrive CCC, CIC, NBT, and NBT EVO systems manufactured by Harman
• Audi — A1 8X, A3 8V/8V facelift, A4 B8/B9, A5 8T, A6 C7, Q2, Q5 8R — Audi MMI 3G+, MIB2 units by Philips/Harman and Harman
• Mercedes-Benz — C-Klasse W204/W205, E-Klasse W212/W213, A-Klasse W176/W177, B-Klasse W246, CLA C117, GLC X253 — Becker/Harman and Harman Audio 20/COMAND NTG4/5 units
• Volvo — XC90 II, XC60 II, V60, V40 — Harman/Denso Sensus Connect and HU-850 platform

For the full list of supported makes, visit radiocodelookup.com/brands.

How Harman Systems Lock

Harman OEM units span two very different security models depending on their generation:

1. Code-based (older generation): The radio stores a theft-protection PIN independently of the vehicle. A battery change triggers a code prompt. This applies to BMW Business CD (GR serial), Audi Concert/Symphony (AUZ serial), Mercedes Audio 10/20 (BE serial), and equivalent units up to roughly 2014–2016 model years.
2. Vehicle-bound (modern generation): Newer Harman systems — BMW iDrive NBT EVO, Audi MMI 3G+, Mercedes COMAND NTG5, Volvo Sensus — pair cryptographically to the vehicle's VIN and do not use a card code at all. After a battery change these systems reactivate automatically via the CAN bus, or require dealer diagnostic reactivation if the unit was removed and refitted.

Serial Number Format

For units that do use a standalone code, the serial prefix depends on the vehicle brand:

• BMW (Business CD, Becker 2000, Navigation): GR prefix serial on casing label, e.g. GR1234567. Also BP/CL on some older units.
• Audi (Concert, Symphony, MMI older gen): AUZ 14-character serial on casing
• Mercedes (Audio 10, Audio 20, older COMAND): BE prefix serial on casing label
• Volvo (HU-850, Sensus Connect): Plain alphanumeric serial in system settings

How to Find the Serial Number

1. BMW: Remove the unit with DIN extraction keys; GR serial on the top casing sticker. Alternatively, on some vehicles, navigate to Settings → System Information on the iDrive screen.
2. Audi MMI: Hold presets 1 and 6 simultaneously (ignition on, SAFE mode) to scroll the AUZ serial on-screen. Or navigate to Car → MMI Information on the MMI screen.
3. Mercedes: BE serial on casing (remove with DIN clip release), or navigate to Vehicle → Settings → System Information for COMAND units.
4. Volvo: Settings → System Information on the touchscreen.

How to Enter the Code

• BMW Business CD (GR serial): Preset buttons 1–4 to cycle digits; seek button to confirm.
• Audi Concert/Symphony (AUZ serial): Preset buttons 1–4 with the seek/scan button to advance; hold to confirm. On MMI-equipped cars, use the MMI controller to navigate the PIN entry screen.
• Mercedes Audio 20 button units: Preset buttons 1–4 to set digits; hold AM/FM or seek button to confirm the five-digit code.
• Mercedes COMAND controller: Rotate and push the COMAND knob to set digits; navigate to OK to confirm.
• Volvo (touchscreen): Tap the four digits on the PIN pad and confirm.

Vehicle Brand	System	Serial Prefix	Security Type
BMW (pre-2015 NBT)	Business CD, CCC/CIC	GR / BP	Code-based
BMW (NBT EVO, post-2015)	iDrive NBT EVO	N/A	Vehicle-bound (VIN)
Audi (pre-2016)	Concert, Symphony, MMI 3G	AUZ (14 chars)	Code-based
Audi (MIB2, post-2016)	MMI 3G+ / MIB2	AUZ / N/A	Komponentenschutz (dealer)
Mercedes (pre-NTG5)	Audio 10/20, COMAND NTG1–4	BE	Code-based
Mercedes (NTG5+)	COMAND NTG5, MBUX	N/A	Vehicle-bound (dealer)

Troubleshooting

• BMW iDrive shows SAFE but no code prompt: Older BMW units with CCC or CIC iDrive show SAFE briefly and then prompt for a code. If no prompt appears and the system boots normally, it is likely already unlocked or is a vehicle-bound unit that does not require a code.
• Audi MMI shows Komponentenschutz: This screen appears on MIB2/MIB3 units and indicates VIN-based component protection. A dealer must reactivate the unit using VAG diagnostic tools (ODIS). There is no PIN code for this system.
• Mercedes MBUX / COMAND NTG5 — no code request: These systems are vehicle-bound. After a battery change they should reactivate automatically. If they do not, consult a Mercedes dealer or a specialist with XENTRY diagnostic access.
• Volvo Sensus no code required: Modern Volvo Sensus Connect (XC90 II, XC60 II) is VIN-paired. It does not use a radio code. If the system fails to restart after a battery change, hold the power button for 10 seconds to force a cold reboot.

Frequently Asked Questions

Does BMW iDrive need a radio code?

It depends on the generation. E-series BMW Business CD and Navigation CD units (pre-2004) use GR serials and standalone codes. From the E-series iDrive CCC (2001 onwards) through to NBT EVO, the situation varies — CCC and CIC units fitted before approx. 2013 may prompt for a code; NBT EVO units are generally vehicle-bound and do not. Check whether a code prompt appears on startup after your battery change.

What is Harman Kardon — is it different from Harman?

Harman Kardon is Harman International's premium audio brand, typically denoting upgraded speaker systems with amplified outputs. The head unit itself may still be a standard Harman unit with a Harman Kardon badge. The code system (if applicable) is the same regardless of the audio upgrade level.

My Audi A4 B8 shows SAFE on the concert unit — where is the AUZ serial?

The Audi Concert on the A4 B8 supports the on-screen shortcut: with the ignition on and the unit in SAFE mode, press and hold presets 1 and 6 simultaneously for two seconds. The 14-character AUZ serial scrolls across the display. No need to remove the unit.

Can a Harman unit be permanently locked?

Older code-based Harman units (GR/AUZ/BE serial) use time-based lockouts (typically one hour) rather than permanent locks. You cannot permanently lock them by entering wrong codes — you can only trigger the wait period. Modern vehicle-bound units cannot be unlocked with any code, correct or otherwise; they require dealer reactivation.

Where can I get the code for my GR serial BMW or BE serial Mercedes?

Visit radiocodelookup.com/brands, select BMW or Mercedes from the brand list, enter your GR or BE serial number, and the unlock code is delivered to your email address. The process typically takes only a few minutes.