Description
Airbag control unit for Citroën C4 first series. The unit is fully functional.
This airbag control unit (SRS ECU) is designed for the Citroën C4 first generation and is identified by the listed part numbers. It is intended primarily for professional workshops and experienced DIY mechanics who search parts by product code. The unit monitors crash sensors and controls airbag and seatbelt pretensioner deployment to protect vehicle occupants in the event of a collision.
Key Benefits
- Direct replacement for original Citroën SRS control units, simplifying repairs when part numbers match.
- Compact, vehicle-specific design ensures correct communications with airbag sensors and safety restraints.
- Allows re‑establishment of SRS functionality after removal and correct initialization.
Technical Information
- Manufacturer: Stellantis (Citroën)
- Model: Citroën C4 I (First Generation)
- Product Codes: 9662643680
- Other Numbers: 603725800, 654633, 654634
Compatible Models
Citroën C4 First Generation (C4 I), model years approximately 2004–2010. Compatibility depends on equipment level and the exact part number — customers commonly locate this unit by the listed codes.
Installation Recommendations
- Always disconnect the vehicle battery and wait at least 10 minutes before starting work to allow SRS capacitors to discharge.
- Access the unit carefully—SRS control units are typically located inside the passenger compartment, often beneath the center console or under the front seats; remove trim panels without forcing clips.
- Handle connectors by the housing, do not pull wiring; ensure locking tabs are fully disengaged before separation.
- After mechanical installation, use a compatible PSA diagnostic tool (for example DiagBox/Lexia) to perform SRS system checks, clear fault codes and complete any required initialization or coding.
- If the unit stores crash data from a prior deployment, professional erasure/initialization with diagnostic equipment will be necessary before returning the vehicle to service.
- Observe manufacturer torque settings and assembly order for trim and fasteners to avoid rattles or damaged clips.
Replacement Procedure (Overview)
General replacement steps: disconnect the battery and wait; remove relevant trim to reach the SRS unit; unplug connectors and remove mounting fasteners; fit the new unit, reconnect connectors and fasteners; reconnect the battery and run diagnostic checks to confirm SRS system status and clear any stored faults. Always follow the vehicle manufacturer service manual for safe working procedures.
Why The Part Most Often Fails
- Activation During A Collision: Deployment of airbags records crash data and often requires module replacement or professional reinitialization.
- Water Ingress And Corrosion: Moisture or fluid leaks into the cabin can corrode connectors and printed circuit boards.
- Electrical Events: Voltage spikes, incorrect jump-starting or problems with charging systems can damage the unit.
- Connector Or Wiring Damage: Broken pins, poor repairs, or mechanical strain lead to intermittent faults or loss of communication with sensors.
Notes For Workshops And Mechanics
When sourcing replacement SRS control units, match the exact part number to reduce diagnostic time. After installation, verify full system operation with a diagnostic scanner and follow safety rules when working around airbag components. If you are not equipped to perform SRS reinitialization, consult a qualified technician with PSA-compatible diagnostic equipment.
