The RD4 D2 N2 CD radio is a direct-fit multimedia unit commonly found in PSA group vehicles. Designed for professional garages and experienced DIYers, this unit delivers original functionality including CD playback and dual antenna support. The radio is often sought by part number (9659142777, 7643141392) so listing OEM references helps you find an exact replacement quickly. If you need a reliable OEM radio that matches factory controls and dashboard integration, the RD4 is a practical choice for Peugeot 407 and compatible Citroën models.

Technical Information

Manufacturer: Stellantis (Citroën / Peugeot)

Model: Peugeot 407 (compatible with some Citroën models, e.g. C5 II)

Product Codes: 9659142777, 7643141392

Other Numbers: 6564W5, 6564W6, 16085109YW

Key Features

• RD4 D2 N2 CD player unit — factory-fit functionality
• Two antenna inputs for improved radio reception or compatibility with diversity systems
• Direct dash integration with factory controls and vehicle wiring
• Requires vehicle coding/programming after installation to restore full functionality

Installation Recommendations

• Always disconnect the vehicle battery before starting removal or installation to avoid short circuits and protect vehicle electronics.
• Use appropriate trim tools to remove surrounding panels without damaging dashboard plastics.
• Carefully unplug connectors and note antenna plugs: this unit has two antenna inputs that must be reconnected correctly.
• After mechanical installation, the radio must be coded/programmed to the vehicle using PSA diagnostic equipment (e.g. DiagBox/Lexia) to restore full integration with vehicle electronics and steering wheel controls.
• If you lack diagnostic equipment, have coding performed by a technician with PSA service tools; incorrect coding may cause limited functionality or loss of features.

How To Replace

1. Disconnect the negative battery terminal and wait a few minutes.
2. Remove trim panels around the radio using plastic pry tools to avoid scratching.
3. Unscrew and slide out the radio unit, then disconnect the harnesses and antenna leads.
4. Fit the replacement unit, reconnect antenna cables and harnesses, secure the radio, and refit trim.
5. Reconnect the battery and perform vehicle coding/programming so the unit is recognized and fully functional.

Why This Part Fails Most Often

Factory radios like the RD4 may develop faults over time due to several causes: CD mechanism wear or mechanical failure, moisture ingress causing corrosion on connectors or antenna sockets, thermal stress on internal electronics, damaged or corroded antenna connectors leading to poor reception, and software/EEPROM issues that require reprogramming. In many replacement cases, the unit itself is functional mechanically but needs proper coding to the vehicle to re-enable features and communication with the vehicle network.

Notes For Professionals

This unit is commonly searched by its OEM numbers — include those codes in searches to quickly locate matching parts. Installation and final commissioning require knowledge of PSA vehicle electronics and access to suitable diagnostic tools for coding.

Compatibility And Fitment

Primarily fitted to Peugeot 407 vehicles. It is also compatible with certain Citroën models that use the RD4 radio platform, such as C5 II. Confirm dashboard opening and connector compatibility before installation.

Recommendation

Ideal for workshops and experienced DIYers who can perform physical replacement and arrange coding with PSA diagnostic equipment. Proper installation and coding restore factory integration, steering wheel controls, and full radio functionality.

Product Overview

This original-equipment RD4 CD radio is a direct-fit audio unit taken from a Peugeot 407. It is a robust OE-style head unit designed for workshops and DIY mechanics who need a reliable replacement radio with CD playback and improved reception thanks to dual antenna inputs. The unit is widely searched by its product numbers, so listing the reference codes below will help you find the correct fit quickly.

Key Features

• RD4 D2 N2 CD head unit — factory standard for many PSA models
• Two Antenna Inputs — supports antenna diversity or connection to external aerial/amplifier systems for better reception
• CD Playback plus AM/FM radio functionality
• Designed as a direct OE replacement for vehicles originally fitted with RD4 units
• Supplied used (original vehicle unit) — requires diagnostic coding to enable full operation in the replacement vehicle

Technical Information

• Manufacturer: Stellantis / Peugeot-Citroën
• Model: RD4 D2 N2
• Product Codes: 9646871777, 7643141392
• Additional Numbers: 6564W5, 6564W6, 16085109YW

Compatibility

The unit originates from a Peugeot 407 and is intended as a replacement for vehicles originally equipped with the RD4 series radio. Many buyers search for this item using the product codes listed above. Ensure your vehicle originally used an RD4-type unit before installation to avoid wiring or coding issues.

Function And Behaviour

The RD4 radio provides CD audio playback and FM/AM reception. Dual antenna inputs improve signal quality and can support external amplifier connections or antenna diversity systems used on some PSA models. When installed and coded correctly, the unit integrates with vehicle audio systems and steering wheel controls where applicable.

Replacement Procedure (General Guide)

• Prepare tools: trim removal tools, radio removal keys (if required), Torx/screwdriver set.
• Disconnect the negative battery terminal before starting to avoid electrical damage or faults.
• Remove dashboard trim panels carefully to access the radio mounting frame.
• Unscrew and slide out the radio; disconnect the main harness, antenna connectors (note there are two), and any separate amplifier or CAN connectors.
• Fit the replacement unit by reversing removal steps. Secure mounting screws and refit trim panels.
• Perform diagnostic coding to pair the radio to the vehicle (see Coding section below).

Coding And Commissioning

This RD4 unit requires diagnostic coding to enable full functionality in the replacement vehicle. Without proper coding (performed with compatible PSA diagnostic tools), features such as radio enablement, display messaging and steering wheel controls may not work. Coding must be performed by a workshop with PSA-capable diagnostic equipment.

Installation Recommendations

• Always Disconnect The Battery Before Removal/Installation To Prevent Electrical Damage.
• Use Proper Trim Tools To Avoid Breaking Dash Clips And Finish Panels.
• Label Or Photograph Connectors Before Disconnecting To Ensure Correct Reassembly.
• Have A Professional With PSA Diagnostic Equipment Perform The Final Coding/Activation If You Do Not Have The Required Tools.

Why This Part Most Often Fails

Common causes of RD4 radio failures include:

• Mechanical Wear In The CD Mechanism — frequent use and age can cause the loader or laser assembly to fail.
• Moisture Ingress And Corrosion — water or humidity can corrode connectors or internal boards, especially when dash seals are compromised.
• Thermal Stress And Solder Joint Fatigue — repeated heating/cooling cycles can lead to cracked solder joints and intermittent faults.
• Connector Or Wiring Issues — poor contacts or damaged antenna leads reduce reception or cause the unit to lose power/functions.

Notes For Workshops And DIY Mechanics

Because the radio is an original PSA unit, installation and coding workflows are standard for Peugeot/Citroën workshops. Having the product codes to hand will speed up parts lookup and compatibility checks. This unit is ideal for mechanics looking for a cost-effective, direct-fit replacement for vehicles originally equipped with RD4 radios.