Citroën C4 Radio Code — Unlock It Online

If your Citroën C4 radio is requesting a code — or showing a blank screen after a battery change — you need the four-digit unlock code matched to your head unit's serial number. The C4 uses the same PSA Group (Peugeot-Citroën) anti-theft platform as most Peugeot models, so the process for finding the serial and entering the code is consistent across both generations. Here's everything you need to know.

Why Does the Citroën C4 Radio Lock?

PSA Group fitted radio security codes to all Citroën and Peugeot models from the early 2000s onwards. When the battery is disconnected or fails, the RD4, RD45, RD5, or RT6 head unit detects the power loss and locks itself. The display typically goes blank or shows CODE. This is a theft deterrent — a removed radio is useless without the code linked to its serial number. Both C4 generations (2004–2010 and 2010–2018) are affected.

Finding the Serial Number on a Citroën C4

The serial number is stored in the radio's memory and can usually be retrieved without removing the unit. The method is the same for RD4/RD45 and RD5/RT6 radios:

Button combination (most C4 models): With the radio switched off, press and hold preset buttons 1 and 6 simultaneously (or 3 and 6 on some variants) for about five seconds. The serial number will appear on the display.
Touchscreen (RT6, C4 II): On C4 II models with the RT6 touchscreen, navigate to Settings → System Information to find the serial.
C7 barcode label: The serial is printed as a barcode on a label inside the unit — accessible if you remove it using a plastic trim tool. The serial format on Citroën's C7 barcodes is typically eight to ten characters.

Once you have the serial, order your Citroën C4 radio code here and have it in your inbox within minutes.

How to Get Your Citroën C4 Radio Code

Retrieve the serial number using one of the methods above.
Visit radiocodelookup.com and enter the serial number and your e-mail on the order form.
Complete secure payment; the four-digit code arrives by e-mail immediately.
Enter the code on the head unit using the method described below.

Entering the Code on a Citroën C4

Entry depends on whether your C4 has a button-based or touchscreen radio:

C4 I (RD4 / RD45, Philips/VDO): Press preset buttons 1–4 to select each digit of the code (e.g. for digit 3, press button 1 three times). Press a dedicated OK or Seek button to confirm and move to the next digit. After the final digit, press and hold to confirm the full code.
C4 II (RD5 / RT6, Bosch/Clarion, 2010–2018): With the unit powered on, the code prompt appears on the screen. Tap the on-screen digits or use the physical preset buttons depending on the radio variant, then press OK to confirm.

Citroën C4 Generations: Radio, Manufacturer, and Entry Method

Generation	Years	Head Unit	OEM Manufacturer	Entry Method	Max Attempts
C4 I	2004–2008	RD4 / RD45	Philips / VDO	Buttons 1–4 + OK	10
C4 I facelift	2008–2010	RD4 / RD45 / RD5	Philips / VDO	Buttons 1–4 + OK	10
C4 II	2010–2018	RD5 / RT6	Bosch / Clarion	Buttons or touchscreen	10

Troubleshooting Citroën C4 Radio Problems

Blank screen: This usually means the radio is waiting for power to stabilise. Turn the ignition to position II (accessories on) and wait 30 seconds. A CODE prompt should appear.
CODE prompt: The radio is ready for the four-digit unlock code. Enter carefully as described above.
WAIT or locked after wrong code: After too many incorrect attempts (up to 10 on most PSA units), a temporary lockout is imposed. Leave the ignition on for one hour, then try again with the correct code.
RT6 says "Invalid Code": Double-check the serial number you submitted matches the unit exactly. The RT6 is case-sensitive on its serial display — transcribe every character carefully.

Frequently Asked Questions

How do I get the serial number on a Citroën C4 without removing the radio?

On most C4 models, press and hold preset buttons 1 and 6 simultaneously for five seconds with the radio switched off. The serial number will scroll on the display. On C4 II models with RT6, navigate to Settings → System Information via the touchscreen.

What is the difference between an RD4 and an RD5 in the Citroën C4?

The RD4 (and RD45) is the CD-based head unit fitted to C4 I models (2004–2010), manufactured by Philips/VDO. The RD5 and RT6 are later units fitted to C4 II (2010–2018), made by Bosch/Clarion, with CD and MP3 playback plus an optional touchscreen. Both types are code-protected and both use the same serial-based unlock process.

My Citroën C4 radio shows CODE after a battery change — what should I do?

The CODE prompt means the radio is ready for your unlock code. Retrieve the serial number using the button combination (presets 1 + 6, held five seconds), order the code online, and enter it using the preset buttons or touchscreen as described above.

How many times can I enter the wrong code before the Citroën C4 radio locks?

PSA Group radios (RD4/RD45/RD5/RT6) allow up to 10 attempts before imposing a one-hour wait. The lockout is temporary — leave the ignition on for an hour and the CODE prompt reappears.

Can I get a radio code for a second-hand C4 or a replacement unit?

Yes. The code is tied to the head unit's serial number, not the car. Whether the radio came with the car or was fitted afterwards, the process is identical — just enter the unit's serial on the order page. Order your Citroën C4 code here.