Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
SIR System Description and Operation: Notes
The supplemental inflatable restraint (SIR) is a safety device used in conjunction with the seat belt. The air bag does not replace the function of the seat belt. The driver and the passengers must always fasten their seat belts and adjust them for a proper fit.
The SIR is designed to protect the driver and the front seat passenger in the event of a significant frontal impact to the vehicle. The air bags deploy if the force is applied from a direction within 30 degrees of the vehicle center line.
The SIR system consists of the following components:
- Driver air bag module
- Driver side air bag module
- Passenger air bag module
- Passenger side air bag module
- Driver and front passenger seat belt pretensioners, and load limiter for some models
- Sensing and diagnostic module (SDM)
- Clock spring
- Wire harness and connectors
- AIRBAG indicator on the instrument cluster
- Passenger AIRBAG OFF indicator on the clock screen
- Side air bag sensor
- Occupants classification system (sensor and module) (North America Vehicles)
- Early crash sensor (North America Vehicles)
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.