Airbag Unit Citroën C4 9662643980 603726100

Description

Airbag Control Unit Citroën C4
Fully Functional

This airbag control unit (SRS Module) is a direct-fit used part for Citroën C4 vehicles. It monitors crash sensors and commands the deployment of airbags and seatbelt pretensioners in the event of a collision. Ideal for professional workshops and competent DIY mechanics looking for a replacement unit that carries the original equipment part numbers: 9662643980 / 603726100 (also referenced as 654635 / 654636).

Technical Information

• Manufacturer: Citroën (Stellantis)
• Model: Citroën C4 (First Generation)
• Product Codes: 9662643980, 603726100
• Other Numbers: 654635, 654636

Application / Compatible Models

Designed for Citroën C4 (First Generation) models that use the above part numbers. When searching or ordering, technicians commonly use the product codes 9662643980 or 603726100 to locate the correct unit.

Function

The unit is the vehicle’s airbag (SRS) control module. It continuously monitors inputs from accelerometers and impact sensors, evaluates collision conditions and, if thresholds are exceeded, triggers airbags and pretensioners. It also records fault codes and crash event data to the module memory so that faults can be diagnosed after an incident.

Common Failure Causes

• Deployment During A Collision – Modules replaced after airbag deployment are commonly nonfunctional or locked.
• Electrical Damage – Short circuits, power surges or improper jump-starting can damage the unit.
• Moisture And Corrosion – Water ingress or corroded connectors can cause intermittent faults or complete failure.
• Connector Damage – Broken pins or poor contacts from previous repairs or rough handling.
• Stored Faults – Past sensor faults or previous crash events that were never properly cleared or serviced.

Replacement Procedure

Only follow these steps if you are qualified and have the appropriate tools. Incorrect handling can compromise SRS safety systems.

1. Disconnect the Negative Battery Terminal and wait at least 10 minutes for residual energy in the system to dissipate.
2. Locate the Airbag Control Unit – typically mounted under the center console or beneath a front seat; exact location depends on vehicle specification.
3. Remove Seat/Console Panels As Required To Access The Unit.
4. Unbolt The Unit And Carefully Disconnect Electrical Connectors. Inspect Connector Pins For Corrosion Or Damage.
5. Fit The Replacement Unit, Secure With Fasteners To Specified Torque, Reconnect Connectors Ensuring Proper Engagement.
6. Reconnect The Battery And Use A Diagnostic Tool To Read And Clear SRS Fault Codes, Then Confirm That The Airbag Warning Light Extinguishes After Self-Check.

Installation Recommendations

• Always follow the vehicle manufacturer’s repair manual and safety procedures.
• Use an appropriate diagnostic scanner to read stored crash data and to clear and verify SRS faults after installation.
• If the module shows a recorded deployment event or irreparable internal damage, replace it with a suitable serviceable unit; do not attempt repairs that compromise safety.
• Inspect wiring harnesses and sensors when replacing the module to ensure there are no related faults.
• Professional installation is recommended for correct diagnosis, configuration and safety verification.

Why Choose This Unit

This unit provides a cost-effective replacement option for Citroën C4 owners and workshops when matched to the correct part numbers. It is intended for users who need an original-equipment reference and wish to restore full SRS functionality when the existing module is faulty or after non-deployment related failures.