Whenever you face the temperature warning light, you should stop driving the car immediately. It is because the engine of the car is overheating. If you keep driving it will destroy the pumps and hoses inside. Open the engine for a while, and do not try to open the radiator cap if the engine is still hot. After 30 minutes, you can check the coolant level in the car. If the coolant level is low, fill more coolant inside. If the coolant level is full, then may be there is coolant leak in your car. In that case, take your car to the service station to diagnose the coolant leak.