TOYOTA 2010 Prius - Manual (Page 532)

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5-2. Steps to take in an emergency
Have the vehicle inspected immediately.
Failure to investigate the cause of the following warnings may lead to
the system operating abnormally and possibly cause an accident.
Have the vehicle inspected by your Toyota dealer immediately.
Warning message Details
(If equipped)
Indicates a malfunction in the LED headlight system.
Indicates a malfunction in the parking lock system.
(Flashing)
(If equipped)
Indicates a malfunction in the pre-collision system.
A buzzer also sounds.