Lexus IS 350C 2012 Manual page 208

2-4. Using other driving systems
Radar sensor and grille cover
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Always keep the sensor and grille cover clean to ensure that the vehicle-to-vehicle
distance control operates properly. (Some obstructions, such as snow, ice or plastic
objects, cannot be detected by the obstruction sensor.)
Dynamic radar cruise control is canceled if an obstruction is detected.
Warning lights, messages and buzzers for dynamic radar cruise control
■
Warning lights, messages and buzzers are used to indicate a system malfunction or
to inform the driver of the need for caution while driving. (P. 504)
208
Grille cover
Radar sensor