How Automotive Warning Lights Work

Types of Automotive Warning Lights

Although vehicles from 1996 and after are required to have the OBD-II system, many vehicles prior to this date were already using warning lights on the dashboard. The lights can vary slightly from vehicle to vehicle, but the most common warning light (and one required by law) is the check engine light. The check engine light or service engine soon light is also commonly known as the Malfunction Indicator Lamp, or MIL.

The MIL is typically a yellow or orange-color light and may display the image of an engine. When the MIL comes on, taking your car to the nearest vehicle maintenance shop may not be immediately necessary; that is, unless the light starts flashing [source: Consumer Reports]. A flashing MIL indicates that there is a serious problem with a part of your engine, or perhaps a potentially serious problem, and immediate auto maintenance is required.

The brake warning light is another common dashboard warning light that will display when an area of the braking system needs attention. The light is typically red, and will usually display the word "brake." If the anti-lock braking system (ABS) warning light comes on, then there's a problem with the ABS and it may shut itself off until the issue is corrected. Normal brake functions can still occur even with the ABS shut-off, but the vehicle should definitely be taken to an automotive maintenance shop as soon as possible.

In addition to the check engine and brake warning lights, there are other important warning lights including the battery warning light, which can indicate that the battery has a low charge, that the alternator is not charging the battery properly, or possibly both. The oil warning light indicates low oil pressure in the engine or that the engine is running low on oil. The airbag warning light denotes that one or more airbags may not function correctly in an accident. The temperature warning light is usually a thermometer symbol and will display when the engine is overheating. Since each vehicle can have different types of warning lights, check the vehicle owner's manual for the most accurate description of each light.

Let's go on to the next page to find out what triggers these lights to come on and the maintenance your car may require.