SIS (Side Impact Sensor) – Function, Symptoms, Location, Diagnosis, and Possible DTCs

The SIS (Side Impact Sensor) is an essential component of the Supplemental Restraint System (SRS). It detects side collisions and sends impact data to the Airbag Control Module (ACM). Based on the severity of the crash, the ACM may deploy the side airbags and seat belt pretensioners.

What Does SIS Stand For?

SIS = Side Impact Sensor

Main Functions

• Detects side collisions.
• Sends crash information to the Airbag Control Module.
• Activates side airbags when necessary.
• Works with front impact sensors and rollover sensors.

Common Symptoms

• Airbag warning light ON.
• SRS fault codes stored.
• Side airbags disabled.
• Communication or sensor circuit faults.

Typical Location

The Side Impact Sensor is commonly mounted inside the B-pillar, front doors, rear doors, or lower body structure. Sensor location varies by vehicle manufacturer and model.

Simple Signal Diagram

 Side Impact
      │
      ▼
+------------------+
|       SIS        |
+------------------+
      │ Signal
      ▼
+------------------+
| Airbag Control   |
| Module (ACM)     |
+------------------+
      │
      ▼
 Side Airbags
 Pretensioners

Possible Diagnostic Trouble Codes (DTCs)

• B1620 – Side Impact Sensor Circuit Fault
• B1621 – Side Impact Sensor Signal Fault
• B1622 – Side Impact Sensor Communication Fault
• B1623 – Side Impact Sensor Internal Failure
• B1630 – Left Side Impact Sensor Fault
• B1631 – Right Side Impact Sensor Fault
• B0090 – Left Side Impact Sensor
• B0091 – Left Side Impact Sensor Circuit
• B0092 – Right Side Impact Sensor
• B0093 – Right Side Impact Sensor Circuit

Diagnosis Tips

• Read SRS codes with a professional scan tool.
• Inspect the sensor connector for corrosion or loose pins.
• Check wiring continuity between the SIS and ACM.
• Replace the sensor if internal failure is confirmed.

Important Note

The exact DTC numbers, wiring diagrams, connector pinouts, and sensor locations vary by manufacturer. Some vehicles use manufacturer-specific SRS codes instead of generic B-codes.

Frequently Asked Questions

Can a faulty SIS illuminate the airbag warning light?

Yes. A malfunctioning Side Impact Sensor commonly triggers the SRS warning indicator.

Can the SIS be repaired?

Most Side Impact Sensors are replaced rather than repaired.

Can I drive with a failed SIS?

The vehicle can usually be driven, but the side airbag system may not provide protection during a side collision.