446 airbag control unit fault

What does error code 446 in the airbag control unit indicate?

Error code 446 indicates a serious malfunction in the airbag control unit (SRS). In most cases, it points to an internal hardware failure that prevents communication with the diagnostic system. The control unit can no longer ensure its safety functions, which is why the airbag warning light remains illuminated.

This specific diagnostic code signals a critical issue directly within the control unit itself. Internal electronics, such as the microprocessor or memory modules, are unable to perform their required self-tests successfully.

From a safety perspective, this means the entire restraint system (Supplemental Restraint System, SRS) is deactivated as a precautionary measure. In the event of a crash, the airbags and seatbelt pretensioners would not deploy. The error can only be cleared once the underlying hardware cause has been resolved.

How do you recognize error code 446?

The main symptom of error code 446 is a permanently illuminated airbag warning light on the instrument cluster. Additionally, stable communication with the airbag control unit via a diagnostic tool often cannot be established. Attempts to clear the fault memory fail because the error reappears immediately.

The most obvious sign is the continuously lit airbag warning light. It does not turn off after starting the vehicle, indicating a persistent, safety‑relevant system fault.

Another clear symptom is loss of communication. During diagnostics, workshops find that the airbag control unit is no longer accessible through the OBD interface, and diagnostic requests remain unanswered.

As a result, errors stored in the fault memory cannot be erased. Even after attempting to clear them, code 446 is promptly reset because the hardware issue persists and continues to be detected by the system.

In many cases, the entire airbag system becomes locked out. This particularly occurs after a crash where the airbags have deployed and crash data has been recorded in the unit’s memory.

What causes error code 446?

The most common cause of error code 446 is an internal defect within the airbag control unit itself—a hardware failure. Other reasons include crash data stored in the control unit following an accident, which triggers a system lockout. External factors such as faulty sensors, cable breaks, or moisture damage can also lead to this error.

First and foremost is a defect in the control unit’s hardware components. This may involve solder joints, processors, or other electronic parts that fail due to aging, vibration, or thermal stress.

A very common cause is the storage of crash data. After an airbag deployment, the control unit locks itself for safety reasons and reports error 446. Professional resetting is required to restore functionality.

Problems in the airbag system’s peripherals can also contribute to this error. These include a damaged coil spring on the steering wheel, defective impact sensors, or faulty connectors—such as those under the seats.

External influences like moisture ingress represent another potential source of failure. Corrosion and short circuits on the circuit board can irreparably damage sensitive electronics and trigger error code 446.

Which models experience error code 446?

Error code 446 specifically affects high-performance vehicles such as the Lamborghini Aventador. Various Mercedes-Benz models, including vans like the Vito, Viano, and Sprinter, are also frequently affected. At Airbag24, we specialize in repairing these particular control units.

At Airbag24, we primarily repair airbag control units displaying error code 446 for the following models:

Lamborghini: Aventador LP700-4 (model years 2011–2017)

Mercedes-Benz: Vito, Viano, and Sprinter

For these models, repair offers a proven, cost-effective alternative to the expensive replacement of the control unit with a new one.

How is error 446 repaired?

Professional repair of error 446 focuses on restoring the removed airbag control unit. At Airbag24, after receiving the unit, we analyze it, replace defective hardware components at the circuit board level, and erase stored crash data. The unit is then thoroughly tested and fully functional again.

The process begins with the proper removal of the airbag control unit from the vehicle. It is crucial that this task be performed by trained personnel to avoid safety risks.

After securely sending the unit to Airbag24, a comprehensive diagnosis is performed in our laboratory. Our technicians identify the exact source of the fault on the circuit board, whether it’s a hardware defect or a lockout caused by crash data.

The actual repair involves replacing defective electronic components and professionally erasing the crash data, restoring the control unit to its original, fully functional condition.

Following successful repair, the control unit undergoes a functional test to ensure proper operation. We provide 2 years' statutory liability for defects on all repairs. The refurbished unit can then be reinstalled in the vehicle using a plug-and-play process.

Is Repair Worth It for Error Code 446?

Repairing the airbag control unit when error code 446 occurs is highly cost-effective. The cost is often just a fraction of what a new control unit would cost from the manufacturer. Additionally, there’s no need for expensive re-coding, saving both time and money.

The biggest advantage is the significant cost savings. While a new part often costs several hundred euros, repair offers a much more affordable solution that protects your budget while restoring full functionality.

A repaired control unit is a plug-and-play solution. Since the original vehicle configuration is preserved, extensive and costly reprogramming or coding at an authorized dealer is unnecessary.

Moreover, refurbishment is a sustainable alternative. Rather than discarding a complex electronic component, it is expertly repaired, conserving valuable resources. With 2 years' statutory liability for defects on the work performed, repair provides a safe and reliable solution.