Description
Airbag Control Unit For Citroën C4 First Series. Fully Functional.
This Airbag Control Unit (SRS Module) is a direct-fit electronic safety component for Citroën C4 first-generation vehicles. Ideal for professional workshops and experienced DIY mechanics, it restores proper operation of the Supplemental Restraint System after unit replacement or repair. The unit is commonly referenced by part numbers 9662643980 and 603726100, making it easy to find in searches and diagnostics. Installing a correct and functioning airbag control unit is essential to clear SRS faults, re-enable airbags and seatbelt pretensioners, and ensure the vehicle meets its designed crash protection standards.
Technical Information
- Manufacturer: Stellantis (Citroën / Peugeot)
- Model: Citroën C4 I (First Generation)
- Product Codes: 9662643980, 603726100
- Other Numbers: 654635, 654636
Function And Application
The airbag control unit (SRS ECU) continuously monitors crash sensors, seatbelt pretensioners and airbag circuits. In the event of a collision it evaluates sensor signals and triggers the appropriate restraint devices. It also stores fault codes and, in many cases, crash event data. This unit is intended for Citroën C4 first-series models and may be used on compatible Stellantis platforms that share the same part numbers.
Replacement Procedure (Overview)
- Safety First: Disconnect the vehicle battery and wait at least 10 minutes to allow capacitors to discharge before beginning work.
- Access: Locate the unit (position varies by equipment level; commonly found under the center console, under a seat or behind trim panels). Remove surrounding trim and fasteners carefully.
- Disconnect: Unplug all connectors using appropriate release tools; avoid pulling on wiring.
- Remove/Install: Unbolt the module, fit the replacement unit, secure fasteners and reconnect plugs with correct seating.
- Initialization: After installation, clear stored SRS fault codes and perform system checks with a PSA-compatible diagnostic tool (e.g. DiagBox/Lexia/PP2000) to ensure the SRS lamp is extinguished and all sensors communicate correctly.
Installation Recommendations
- Always Disconnect The Battery Before Work: Prevent accidental deployment and protect the module electronics.
- Use Proper Tools: Avoid damaging connectors, wiring or housing. Torque fasteners to manufacturer specifications where applicable.
- ESD Precautions: Handle the module by its housing, avoid opening the unit and protect against static discharge.
- Diagnostics: Use A PSA-Compatible Diagnostic Tool To Read/Clear Faults And Confirm System Readiness After Replacement.
- Professional Assistance: If You Lack The Required Diagnostic Equipment Or Experience With SRS Systems, Seek A Qualified Technician To Complete Final Tests And Initialization.
Reasons For Failure
Airbag control units rarely fail under normal conditions but can become unusable due to crash deployment, water ingress, corrosion, connector damage, electrical surges or previous improper repairs. After Airbag Deployment The Module May Lock Or Store Crash Data And Typically Requires Replacement Or Properly Cloned/Restored Memory To Re-Enable The System.
Notes On Compatibility And Searchability
When searching for a replacement, use the part numbers 9662643980 and 603726100 as primary keywords. Including the vehicle model (Citroën C4 I) and terms like “Airbag Control Unit”, “SRS Module” or “Airbag ECU” will improve search results and help find the correct unit quickly.
