* Faulty Coolant Level Sensor: The sensor itself might be malfunctioning and sending inaccurate readings to the car's computer. This is a common cause.
* Air in the Cooling System: Air pockets trapped in the cooling system can prevent accurate readings from the sensor and can also lead to overheating. Even if the tank and radiator *look* full, air might be preventing proper coolant flow. This often requires "burping" the system to release trapped air.
* Coolant Leak (Slow Leak): You might have a small, hard-to-detect leak. The leak could be so slow that it's not immediately obvious, but enough coolant is escaping to trigger the light. Check all hoses, clamps, the radiator itself, and the water pump for any signs of leakage.
* Head Gasket Failure (Serious): In a worst-case scenario, a failing head gasket could allow coolant to leak into the engine's combustion chambers or into the oil. This is more likely if you're also experiencing other symptoms like white smoke from the exhaust, milky oil, or overheating. This requires immediate attention from a mechanic.
* Faulty Wiring or Computer Issue: There's a possibility of a problem with the wiring connected to the coolant level sensor or a malfunction within the car's computer itself that's misinterpreting the sensor data.
What to do:
1. Check for Leaks: Carefully inspect the entire cooling system for any visible leaks.
2. Try Burping the System: If you're comfortable working on your car, look up how to burp the cooling system for your specific model. This involves opening the bleed valve (often on the radiator or engine block) to release trapped air.
3. Let it Cool Completely: Before checking anything, ensure the engine is completely cool to avoid burns.
4. Replace Coolant Sensor (If necessary): This is a relatively simple repair and is often the culprit for a flashing light with a full system. However, you'll want to verify it's actually the sensor causing the problem.
5. Professional Inspection: If you can't find a leak or resolve the issue yourself, take your car to a mechanic for a proper diagnosis. Ignoring a flashing low coolant light can lead to serious engine damage.
A flashing light is usually more urgent than a steady light. Don't drive the car extensively until you determine the cause to prevent overheating and potential engine damage.
