Airbag control unit with part number 5WK4247

What is the function of the airbag control unit 5WK4247?

The airbag control unit 5WK4247 from Siemens/Bosch, with Hyundai’s equivalent part number 95910-38400, serves as the central control module for the occupant protection system in the Hyundai Sonata. It continuously analyzes data from acceleration and yaw rate sensors to precisely and rapidly deploy airbags and seatbelt pretensioners in the event of a crash.

As an SRS module (Supplemental Restraint System), it is responsible for monitoring the entire passive safety system chain, including front and side airbags, seatbelt pretensioners, and all connected crash sensors.

This unit is typically installed in the center console near the accelerator pedal and connects to the vehicle wiring harness via a lockable connector. This location protects the device from minor damage while ensuring centralized detection of vehicle dynamics.

Why does the 5WK4247 control unit fail?

A failure of the 5WK4247 control unit is usually caused by the storage of crash data after an accident, which triggers an internal lockout. Other causes include hardware defects due to moisture ingress, faulty internal sensor components, or blockage of the module following airbag deployment, preventing communication.

The most common reason for an apparent malfunction is the retention of crash data. Even if airbags did not deploy during a collision, the control unit will self-lock for safety reasons. This condition is permanent and can only be resolved through a targeted reset of the internal memory modules.

Physical defects are also a frequent cause. Moisture intrusion can lead to corrosion on the circuit board and failure of microchips or sensors. Errors such as a “side‑sensor fault” often indicate an internal component issue rather than an external sensor problem.

In some cases, the module becomes completely blocked after deployment and becomes inaccessible to diagnostic tools. This is a safety‑critical feature that requires professional repair and unlocking. Similar, repairable control units can also be found in other Hyundai models, such as the unit with part number 95910-39900.

How do you recognize a defect in the 5WK4247?

A defect in the 5WK4247 airbag control unit is unmistakably indicated by a permanently illuminated airbag warning light on the instrument cluster. Often, no connection can be established between the diagnostic tool and the control unit, or error codes are stored that point to an internal fault or retained crash data.

The primary and most obvious symptom is the continuous illumination of the SRS or airbag warning lamp, signaling that the entire restraint system has been disabled and will no longer provide protective functions in the event of a crash.

Another clear sign is the lack of communication: when the workshop attempts to read the fault memory, the diagnostic tool receives no response from the control unit. The module is essentially “dead” and no longer responds to requests via the OBD interface.

If error codes can be read, they often indicate an “internal control unit fault” or specifically “crash data stored.” These errors cannot be cleared using standard diagnostic methods and require specialized repair of both software and hardware.

In which vehicles is the 5WK4247 control unit installed?

The Siemens/Bosch airbag control unit 5WK4247, with OEM part number 95910-38400, is specifically used across various model series of the Hyundai Sonata. At Airbag24, we have extensive experience repairing this module for the Sonata’s specific generations.

At Airbag24, we service the 5WK4247 part number for the following Hyundai models and series:

Hyundai: Sonata EF (model years 1998–2001), Sonata EF Facelift (model years 2001–2005), and Sonata NF Facelift (model years 2008–2010).

It is crucial that the part number printed on the control unit exactly matches “5WK4247” to ensure compatibility. Installing a unit with a different part number may result in malfunctions within the safety system.

How is the 5WK4247 professionally repaired?

At Airbag24, repairs to the 5WK4247 follow a certified process. Following an initial assessment, stored crash data is erased at the chip level, and defective electronic components—such as processors or sensors—are replaced. Final tests confirm full functionality, backed by 2 years' statutory liability for defects.

Upon receipt of the control unit at Airbag24, a comprehensive diagnosis is first performed. Technicians check communication and analyze the fault memory to determine the exact cause of the defect, whether it’s a crash record or a hardware issue.

The core of the repair process involves erasing the crash data from the internal memory (EEPROM) and resetting the control unit. If components such as ECU chips or internal sensors are defective, they are replaced with high-quality aftermarket parts.

Following the repair, the control unit is tested on a specialized test bench to simulate the proper functioning of all system components. The repaired unit is then fully operational again and does not require re‑coding at the workshop. We provide 2 years' statutory liability for defects on every repair.