0667 - Side impact sensor right 2nd row signal implausible (control unit defective) airbag control unit fault

What does error code 0667 mean?

Error code 0667 indicates an implausible or faulty signal from the side‑impact sensor in the right‑hand, second row of seats. The airbag control unit cannot correctly interpret the data transmitted by the sensor, which often points to an internal defect within the control unit itself, a defective sensor, or issues with the wiring. As a result, the entire airbag system is deactivated for safety reasons.

Technically speaking, the side‑impact sensor—also known as a crash sensor or lateral acceleration sensor—monitors the lateral forces acting on the vehicle. This data is crucial for deploying the side and head airbags at precisely the right moment during a side impact.

The status “signal implausible” means that the values sent by the sensor fall outside the manufacturer‑defined acceptable range or are logically inconsistent with data from other sensors. Consequently, the control unit classifies the sensor as unreliable.

As a consequence, the airbag control unit switches to a safe mode and illuminates the airbag warning light. This ensures that under no circumstances can the airbags deploy erroneously.

How do you recognize error code 0667?

The primary and unmistakable symptom of error code 0667 is the permanently illuminated airbag warning light on the instrument cluster. Additionally, a warning message related to the airbag or restraint system may appear on the display. Reading the fault memory with a diagnostic tool confirms the specific code 0667 and identifies the affected sensor.

The red airbag warning light remains continuously lit after starting the vehicle and does not extinguish as it normally would. This is a clear indication of a safety‑critical fault in the restraint system, requiring immediate diagnosis.

In many cases, although the fault memory can be read, error code 0667 reappears immediately after attempts to clear it. This strongly suggests a permanent hardware defect rather than a sporadic issue.

What causes error code 0667?

The most common cause of error 0667 is an internal hardware defect within the airbag control unit itself, often triggered by aging electronic components or voltage problems. Other reasons include a defective side‑impact sensor, damaged cables, corroded connectors between the sensor and the control unit, and, more rarely, water damage inside the control unit.

A defect in the airbag control unit is the most likely culprit. Internal components on the circuit board can suffer damage due to aging, vibrations (such as those caused by a strong door slam), or voltage fluctuations—like those that may occur after replacing the alternator.

The side‑impact sensor itself can fail. Often designated with part number 5M0909606B, this sensor is installed in the door or B‑pillar and can be damaged by moisture or mechanical stress.

Cable breaks or contact issues in the wiring are also frequent sources of failure. In particular, cable conduits running from the body to the door (A‑pillar) are prone to damage from constant movement.

Often, error 0667 does not occur in isolation. Accompanying error codes such as 0666 (left side‑impact sensor), 04C1 or 04C6 (other side‑impact sensors), B1000, B1010, 65535, or FFFF (power supply, internal control unit defect) frequently indicate a more extensive fault within the control unit.

Which vehicles are affected by error 0667?

Error code 0667 occurs frequently in certain models from the VAG Group. Specifically, the Seat Leon across multiple generations, as well as the VW Passat B6, are commonly affected. At Airbag24, we have already successfully repaired this error on numerous control units from these specific vehicle lines and are familiar with their typical weak points.

At Airbag24, we regularly repair error code 0667 for the following models:

Seat: Leon 2 [1P] (2005–2009) and its facelifted version (2009–2012), Leon 3 [5F] (2012–2020), and Leon 4 [KL] (from 2020 onward).

Volkswagen: Passat B6 [3C] (2005–2010).

How is error 0667 repaired?

The repair focuses on eliminating the internal defect in the airbag control unit. After removal and shipment, the device is analyzed and repaired at the hardware level at Airbag24. Defective components are replaced, and if necessary, crash data is erased. Following successful testing, the control unit is fully functional again—plug-and-play—and comes with 2 years’ statutory liability for defects.

Before removing the control unit, a specialized workshop should inspect the sensor and its wiring to definitively rule out these components as the source of the problem. This saves time and ensures that the correct component is sent for repair.

After being sent to Airbag24, a standardized repair process follows. The control unit is opened and subjected to a detailed electronic analysis. Technicians identify the faulty components on the circuit board that are responsible for the implausible signal.

The actual repair is performed at the component level. Defective microprocessors, memory chips, or other electronic parts are expertly replaced. If crash data remains stored in the memory after an accident, it is completely and permanently erased—something impossible with a standard diagnostic tool.

Finally, the repaired control unit undergoes a comprehensive functional test in a specialized testing environment. Upon successful completion, the unit is ready for reinstallation (plug-and-play) and requires no new coding. You receive 2 years' statutory liability for defects on the repair performed.