The low coolant level warning light is usually linked to a floating device inside the coolant expansion tank. When the coolant level gets lower than it should, an electrical switch inside the float will trigger the low coolant level indicator. This indicator may be a light on the dashboard or, on some vehicles, a message that appears in the driver information center, usually located in the center area of the instrument panel.
The Bulb Check: Low Coolant Level Warning Light
When you start the engine, the low coolant level light should come on for 1 to 2 seconds and then go out. If it doesn't go out, the coolant level is too low or there is a problem with the coolant level sensor system. Vehicles equipped with a messaging system will receive the low oil message only if the coolant level is low or if there is a problem with the oil level system.
What to Do: Low Coolant Level Warning Light
If the low coolant level light comes on, or a low coolant level message appears, the engine coolant level should be checked immediately. If the coolant is lower than the marked minimum level on the coolant expansion tank, coolant should be added (make sure it's the proper amount and type of coolant). The vehicle should also be inspected and diagnosed at a qualified repair shop because the low coolant level indicator should only come on if the engine is either consuming excessive coolant or there is a coolant leak. Check in your owners manual for the safe and correct method to check your engine's coolant level.
If the low coolant level indicator comes on and the engine coolant level is normal, there is a problem with the low coolant level warning system. Have the vehicle inspected and diagnosed for this problem at a qualified repair shop.