Citroën C3 Picasso I airbag control unit repair

What is a Citroën C3 Picasso I airbag control unit?

When the ignition is switched on, the airbag warning light comes on briefly and goes out again: behind this is the self-test of the airbag control unit, the central control unit of the restraint system (SRS) in the Citroën C3 Picasso I. It evaluates the signals from the crash sensors and, in an accident, decides within milliseconds which airbags and seatbelt pretensioners deploy.

The control unit is installed in the Citroën C3 Picasso I (2009 to 2017). After start-up it checks the connected sensors and firing circuits and compares their values with stored reference values. If the light stays on afterwards or comes on while driving, the system has detected a fault.

Monitoring also remains active during operation. If an accident occurs, the control unit stores crash data and locks itself.

Why is the Citroën C3 Picasso I airbag control unit defective?

Most often the cause is crash data that was stored after an accident, even if no airbag deployed. Other causes are aged electronic components, cold solder joints, moisture and corrosion on the connectors, and voltage spikes.

Crash data like this cannot be removed with an ordinary diagnostic tool. The control unit then keeps reporting a fault, even though the other components of the system may be undamaged. Voltage spikes can be caused, for example, by a weak battery or a jump start. Components and solder joints also age over the years in the vehicle.

Signs of a defect are a permanently lit airbag warning light, a fault memory that cannot be reset, or a diagnostic tool with no connection to the control unit. In this case, have the control unit checked first before you replace other components of the system.

Common error codes for Citroën C3 Picasso I airbag control unit repair

With a diagnostic tool you read the error codes of the Citroën C3 Picasso I from the fault memory. They point to internal faults in the control unit, to communication disturbances in the vehicle network, to the power supply, or to the firing circuits of the airbags.

These codes are known for this control unit; the selection makes no claim to completeness:

• F620 → Internal fault in the control unit, not specified
• F633 → Internal fault in the passenger airbag firing system, first stage
• F00F → Control unit no longer transmits on the CAN network
• E650 → Control unit supply voltage too high
• B0001 → Driver airbag firing circuit, first stage: resistance too high
• B0028 11 → Front right side airbag: wiring fault, short circuit to ground
• C601 → Driver airbag firing module, first stage: open circuit

A single code does not yet prove that the control unit itself is defective. The cause can equally be connectors, wiring or an airbag module. Only the inspection shows where the fault lies.

What part numbers are available for the Citroën C3 Picasso I airbag control unit repair?

You will find the part number on the label of the control unit. It determines the exact version, because depending on equipment and year of manufacture, different numbers are fitted within the model range of the Citroën C3 Picasso I.

Listed below are part numbers known to us for this control unit. This list is not complete:

• 9677253280
• 9803837180

Compare the number on your unit with the list. This only tells you whether it is the right unit. Whether it is defective only becomes clear from reading out the fault memory or from the inspection.

The route to repair: have the fault memory read out, disconnect the battery and remove the control unit. Then create a repair order online and send in the unit. Checking, repairing and testing usually take 3–4 working days at Airbag24, after which your own control unit is returned to you. The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.