Peugeot RD4 Radio Code
The Peugeot RD4 is a single-DIN CD/tuner head unit manufactured by Philips/VDO and fitted as standard to a huge range of Peugeot models from the early 2000s through to the early 2010s. If your 207, 307, 308 or Partner is displaying CODE on the screen after a battery change, you are in the right place. This guide explains exactly where to find the serial and how to unlock it in minutes.
Why the RD4 Shows CODE
Like all Peugeot OEM radios of its era, the RD4 activates a code lock whenever its power supply is interrupted. This is an anti-theft measure — the unit is worthless to a thief without the matching four-digit PIN. The code is linked to a serial number printed on a C7 barcode label on the unit's casing. You need the serial to look up the code.
Finding the RD4 Serial Number
You have two methods, and the first one avoids removing the radio entirely:
- Preset button trick: Switch the ignition to position II (all dashboard lights on, engine off). Press and hold preset buttons 1 and 4 at the same time. After two to three seconds the display will cycle through a diagnostic sequence and show the serial number. Write down the full string. Note: on some RD4 variants, hold 6 buttons simultaneously or try buttons 1 and 6 if the 1+4 combination does not work.
- Label on the unit: If the button method fails, the radio needs to be extracted. DIN extraction keys slide into the four corner holes in the unit's fascia. Once out, the white C7 barcode sticker on the top or side carries the serial number. The Peugeot serial is typically a mix of letters and numbers without a standard alphabetic prefix like those used by VW or Audi.
Take care to copy every character accurately. Serial numbers containing the letter O versus the digit 0 are a common source of errors.
Getting Your Code and Entering It
With the serial confirmed, visit our Peugeot brand page to order. Once you receive the four-digit code:
- Switch the ignition on and confirm the display shows CODE.
- Use preset buttons 1, 2, 3 and 4 to scroll each digit position to the correct value.
- Press the 5th preset button (or the dedicated confirmation button on your variant) to submit the code.
- The display will briefly show OK and then switch to the radio or last audio source.
Which Peugeot Models Use the RD4?
| Model | Generation | Years | Typical Radio |
|---|---|---|---|
| 206 | 206 | 1998–2009 | RD3 / RD4 / RD43 |
| 207 | 207 | 2006–2009 | RD4 / RD43 |
| 207 Facelift | 207 facelift | 2009–2012 | RD4 / RD45 |
| 307 | 307 | 2001–2005 | RD4 / RD43 |
| 308 | 308 I | 2007–2013 | RD4 / RD45 |
| Partner | Partner II (B9) | 2008–2018 | RD4 / RD45 |
Peugeot shares its radio supply chain with Citroën under the PSA Group umbrella. The RD4 fitted in a Peugeot 307 is mechanically and electronically the same as the one in a Citroën C4 of the same period — and the unlock process is identical.
RD4 vs RD45: Key Differences
The RD45 is an updated version of the RD4, adding Bluetooth audio streaming and a USB port on most variants. The serial number retrieval method and code entry procedure are the same for both. If you are unsure which unit you have, the model designation is usually printed on a small sticker on the front face of the unit or visible through the display.
Troubleshooting
- CODE does not clear after correct entry: Double-check you used buttons 1–4 for digit entry and the fifth button or confirm key to submit. On some RD4 variants the confirmation button is labelled differently.
- WAIT appears after a wrong code: The RD4 imposes a time-delay lockout after incorrect entries. Wait one hour with the ignition in ACC position before trying again.
- Serial via button trick shows only dashes: The unit may need to have been powered on for longer before the diagnostic sequence works. Try again after the radio has been on for at least 60 seconds.
- 1+4 gives a different screen from expected: Some RD4 variants show a service menu rather than the serial directly. Look for a field labelled SN or Serial within that menu.
Frequently Asked Questions
Can I get the RD4 code from a Peugeot dealer?
Yes, a dealer can look it up using the vehicle's VIN if the original purchase records are on file. However, this is only reliable for first-owner cars. For second-hand vehicles, the serial-based lookup is more dependable and faster.
My RD4 serial has letters and numbers mixed — is that normal?
Yes. Peugeot (and Citroën) serial numbers on the C7 barcode are alphanumeric and do not follow the AUZ or VWZ prefix conventions of German brands. Enter the full string exactly as printed.
Is the RD4 code the same as the RD45 code?
Not necessarily — each unit has its own serial and therefore its own unique code. Even if two radios look identical, their serials will differ.
The 1+4 trick shows a serial but the code doesn't work — why?
Double-check the serial character by character, paying particular attention to 0 vs O and 1 vs I. If the serial is correct and the code still fails, the unit may have been re-coded after leaving the factory. In that case, extraction and label inspection is the definitive next step.
Do I need a code after every battery change?
Yes. The RD4 triggers its code lock on every power interruption. Keep the code in your service documents so future unlocks are instant.