Airbag control unit with part number 285010422

What is the function of Airbag Control Unit 285010422?

The Airbag Control Unit 285010422, manufactured by Temic/Bosch, is the central safety module in the Mercedes-Benz SLK-Class R171 Convertible. It continuously monitors data from the vehicle’s sensors, processes it in real time, and, in the event of a crash, activates the necessary restraint systems—such as airbags and seatbelt pretensioners—within milliseconds to protect occupants.

The control unit serves as the brain of the passive safety system. It collects information from acceleration and yaw rate sensors to analyze the type and severity of an impact, ensuring the safety of vehicle occupants.

Based on this analysis, the unit determines which airbags—such as those in the steering wheel or on the A- and B-pillars—should be deployed to minimize injury risk effectively.

Why does Control Unit 285010422 fail?

A common cause of failure for Control Unit 285010422 is an internal electronic defect, often indicated by error code 900E. Other causes include stored, non‑erasable crash data following an accident or a missing vehicle identification number in the unit’s internal memory. These issues are typically hardware‑related.

The specific error code 900E points to an internal electronics fault within the control unit and is a well‑known problem in the SLK R171 series. This is not a software issue but rather a defect in physical components on the circuit board, requiring professional repair.

After a crash, the control unit often locks out access to prevent further use. This lock, known as “crash data,” can be lifted through specialized repair without needing to replace the entire unit.

For the Mercedes-Benz SLK-Class R171, depending on equipment and fault patterns, other control units with similar functions and part numbers may also be relevant, including A1718203126, A1718202426, A1718203626, A1718204726, 0285001984, and 0285010570.

How do you recognize a defect in 285010422?

The clearest sign of a defect in Control Unit 285010422 is a permanently illuminated airbag warning light on the instrument cluster, even without an actual collision. Often, communication with the control unit via an OBD diagnostic tool is no longer possible, or the specific error code 900E is read.

A persistently lit airbag warning light indicates a malfunction in the safety system. In the event of a crash, the vehicle might fail to deploy the airbags, making immediate diagnosis essential.

Another clear symptom is when a workshop’s diagnostic tool cannot access the airbag control unit. The unit fails to respond to queries, complicating precise fault analysis and often pointing to an internal defect.

Before assuming a control unit failure, it’s advisable to check other system components, such as seat occupancy mats or connectors, as these can also produce similar symptoms.

In which models is 285010422 installed?

The Airbag Control Unit with part number 285010422 was specifically developed for the Mercedes-Benz SLK-Class R171. Airbag24 offers professional repair services for this control unit, which is used across all engine options and trim levels of this convertible model produced between 2004 and 2011.

At Airbag24, we repair Control Unit 285010422 for the following specific vehicle model:

Mercedes-Benz: SLK-Class R171 Convertible (model years 2004–2011)

How does repair at Airbag24 work?

Repair at Airbag24 is a straightforward process. After removing the defective unit, simply send it to us. Our technicians perform a detailed analysis and resolve the electronic fault at the component level. Upon successful repair and testing, you’ll receive a fully functional plug-and-play control unit backed by 2 years' statutory liability for defects.

For prompt processing, we recommend reading out the fault memory before removal and including the printout with your package. Important: Before dismantling, ensure the vehicle is de-energized, as the control unit is sensitive to vibrations.

Once submitted to Airbag24, repairs proceed, replacing faulty electronic components—such as those causing error code 900E—or securely erasing stored crash data.

The repair restores the original functionality, eliminating the need for re‑coding in the vehicle. After reinstallation, only the fault memory needs to be cleared at a certified workshop. Using airbag simulators or resistors is life‑threatening and will result in the loss of operating approval.