Rollover Sensor (ROS) – Function, Symptoms, Location, Diagnosis, and Possible DTCs

The Rollover Sensor (ROS) is an important component of the Supplemental Restraint System (SRS) and Electronic Stability Control (ESC) on many modern vehicles. It detects vehicle rollover or an imminent rollover and sends this information to the Airbag Control Module (ACM/RCM/SDM/ORC). If the rollover threshold is reached, the control module may deploy curtain airbags and activate seat belt pretensioners.

What Is a Rollover Sensor?

ROS = Rollover Sensor

Main Functions

• Detects vehicle rollover or rollover risk.
• Measures roll angle and roll acceleration.
• Sends rollover data to the SRS control module.
• Supports curtain airbag deployment.
• Activates seat belt pretensioners during rollover events.

Common Symptoms

• Airbag warning light ON.
• Stored SRS diagnostic trouble codes.
• ESC or Stability Control warning light.
• Curtain airbags may be disabled.
• Communication faults with the SRS module.

Typical Location

The Rollover Sensor is commonly mounted near the vehicle's center of gravity, such as beneath the center console, under the front seats, or integrated inside the Airbag Control Module. The exact location varies by manufacturer and model.

Simple Signal Diagram

 Vehicle Roll
      │
      ▼
+----------------------+
|  Rollover Sensor     |
|       (ROS)          |
+----------------------+
      │ Signal
      ▼
+----------------------+
| Airbag Control Module|
| ACM / RCM / SDM / ORC|
+----------------------+
      │
      ▼
 Curtain Airbags
 Pretensioners

Possible Diagnostic Trouble Codes (DTCs)

• B1638 – Rollover Sensor Circuit (manufacturer-specific)
• B1639 – Rollover Sensor Signal Fault
• B1640 – Rollover Sensor Internal Failure
• U0151 – Lost Communication with SRS Control Module
• U3000 – Control Module Internal Fault
• Manufacturer-specific rollover sensor DTCs

Diagnosis Tips

• Read SRS and ESC fault codes using a professional scan tool.
• Inspect the rollover sensor connector and wiring.
• Verify power, ground, and communication circuits.
• Check for water damage or collision damage.
• Perform calibration if required after replacement.

Important Note

Some vehicles have a dedicated Rollover Sensor, while others integrate rollover detection into the Airbag Control Module or Electronic Stability Control module. Sensor design, wiring, calibration procedures, and DTC definitions vary by manufacturer and model.

Frequently Asked Questions

Can a faulty Rollover Sensor turn on the airbag warning light?

Yes. A malfunctioning rollover sensor can illuminate the SRS warning light and disable curtain airbag deployment.

Does every vehicle have a Rollover Sensor?

No. Many modern SUVs, trucks, and vehicles equipped with curtain airbags include rollover detection, while some passenger cars may integrate this function into another control module.

Does a replacement Rollover Sensor require calibration?

Some manufacturers require calibration or programming after sensor replacement. Always follow the factory service manual.