Airbag control unit with part number 5WK4 3794

What is the function of the Airbag Control Unit 5WK4 3794?

The Airbag Control Unit 5WK4 3794 is a central control module manufactured by Siemens/Bosch for the passive safety system (SRS) in the Hyundai ix55 EN model years 2009 to 2011. It analyzes data from the acceleration sensors and, in the event of a crash, determines whether to deploy the airbags and seatbelt pretensioners to protect the occupants.

As the “brain” of the restraint system, this control unit is responsible for interpreting signals from various crash sensors in the vehicle in real time. Based on this data, it activates the appropriate ignition circuits for airbags and seatbelt pretensioners within milliseconds.

Therefore, proper functionality is critical for safety, as a failure can disable the entire passive protection system of the vehicle.

Why does the 5WK4 3794 control unit fail?

The most common cause of failure for the 5WK4 3794 control unit is the permanent storage of crash data after an accident, which locks the device. In addition, internal hardware defects in microcontrollers, ignition circuit driver stages, or voltage regulators can lead to failure. Communication issues on the CAN bus, as well as corrosion damage caused by moisture, are also typical causes of malfunction.

After an accident in which airbags or seatbelt pretensioners have deployed, the unit stores what is known as a “crash event.” This lock prevents reuse and must be professionally reset—even if all external components have been replaced.

Electronic faults on the circuit board are also widespread. These include defective driver stages for the ignition circuits (squibs), malfunctions in the internal power supply, or damaged measurement channels for the acceleration sensors. A complete loss of communication over the CAN bus may also indicate an internal hardware defect.

In particular for the Hyundai ix55, moisture-related damage is also cited as a cause. Penetrating water can lead to corrosion on the circuit board, destroying conductive traces or sensitive components.

For this functional group, compatible replacement part numbers exist, such as Autoliv’s 624578100, which is designed for the same vehicles.

How do you recognize a fault in the Airbag Control Unit 5WK4 3794?

A faulty 5WK4 3794 control unit primarily manifests as the airbag warning light (SRS lamp) remaining constantly illuminated. Often, communication with the diagnostic tool is no longer possible, or specific error codes such as “internal control unit error” are stored. Even after replacing airbags and sensors following an accident, the error messages persist.

The most obvious symptom is the permanently lit SRS warning light in the instrument cluster. It indicates a critical fault in the restraint system and does not extinguish after starting the vehicle.

Another clear sign is when the workshop cannot establish a connection between the diagnostic tool and the airbag control unit. The unit is then unresponsive and cannot be read.

Error codes such as “Internal Control Unit Error” or “ECU internal fault” are frequently logged in the fault memory. These directly point to a defect in the internal hardware.

In some cases, errors originating from sensors—such as the side impact sensor—are mistakenly reported. Even after these sensors have been replaced, the error code remains because the root cause lies within the control unit itself.

In which vehicles is the 5WK4 3794 control unit installed?

The airbag control unit with part number 5WK4 3794 is specifically used in the Hyundai ix55 EN series produced between 2009 and 2011. At Airbag24, we offer professional repair services tailored precisely to this vehicle model, restoring full functionality to the safety system.

The repair service is designed for the following models and series:

Hyundai: ix55 EN (2009–2011)

How does the repair of the 5WK4 3794 proceed at Airbag24?

Upon submission to Airbag24, the 5WK4 3794 control unit undergoes a detailed diagnosis on a test bench. Depending on the nature of the fault, stored crash data is erased or repairs are performed at the component level. Defective SMD components, such as microcontrollers or voltage regulators, are replaced. A final functional test ensures full operability, backed by 2 years' statutory liability for defects.

The process begins with the proper removal of the control unit at your workshop. You then send us the defective unit along with a completed repair form.

At Airbag24, an initial incoming inspection is conducted to verify the reported fault. Depending on the situation, the repair involves either resetting the crash data to factory settings or replacing defective electronic components—such as ICs, driver modules, or voltage regulators—on the circuit board.

Following successful repair, a comprehensive functional test is performed under simulated vehicle conditions. This ensures that the control unit communicates flawlessly once again and correctly activates all ignition circuits. We provide 2 years' statutory liability for defects on every repair.