Warning lights: Luminous indicator that is usually placed in the dashboards and warns about a possible problem.
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They work either as alarms in case of any irregularities or as simple indicators to show that the systems of the car, such as the handbrake or the turn signal, are activated. They may be red, which indicates the matter is serious, orange, yellow or green, which indicates the matter is not too serious.
My car displayed engine light and i took it for diagnosing,they found that problem is oxygen sensor. I bought another oxygen sensor but problem still exist