In certain low-speed collisions the air bags may not deploy. The air bags are designed not to deploy in such cases because they may not provide benefits beyond the protection of the seat belts.
Front air bags are not designed to inflate in rear collisions, because occupants are moved backward by the force of the impact. In this case, inflated air bags would not provide any additional benefit.
Front air bags may not inflate in side impact collisions, because occupants move in the direction of the collision, and thus in side impacts, front air bag deployment would not provide additional occupant protection.
However, side and curtain air bags may inflate depending on the severity, vehicle speed and angles of impact.
In an angled collision, the force of impact may direct the occupants in a direction where the air bags would not be able to provide any additional benefit, and thus the sensors may not deploy any air bags.
Just before impact, drivers often brake heavily. Such heavy braking lowers the front portion of the vehicle causing it to "ride" under a vehicle with a higher ground clearance. Air bags may not inflate in this "underride" situation because deceleration forces that are detected by sensors may be significantly reduced by such "underride" collisions.
Front air bags may not inflate in rollover accidents because air bag deployment could not provide protection to the occupants.
However, side and curtain air bags may inflate when the vehicle is rolled over by a side impact collision.
Air bags may not inflate if the vehicle collides with objects such as utility poles or trees, where the point of impact is concentrated and the collision energy is absorbed by the vehicle structure.
Hyundai Sonata LF 2014-2019 Service Manual: Front Impact Sensor (FIS) Repair procedures
Removal
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Removal of the airbag must be performed according to the precautions/ procedures described previously.
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Before disconnecting the front impact sensor connector, disconnect the front airbag connector(s).
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Do not turn the ignition switch ON and ...
Hyundai Sonata LF 2014-2019 Service Manual: Auto Head Lamp Leveling Unit Description and Operation
Description
According to driving environment and loading state of
vehicle, head lamp lighting direction is changed to keep the driver's
visibility range and to protect the driver's vision from glare, aiming
at safety driving.
Sensor integrated ECU mounting on the rear center arm drives
...