1. Insufficent coolant hence suggest to top up coolant or check if there is leakage in the system. Coolant can be top up after the engine has cooled down and coolant cannot be mixed between brand.
2. Radiator fan faulty causing the cooling system cannot operate efficiently, need to reduce driving speed or stop the car to call for roadside assist.
3. Water pump failure causing the coolant could not circulate effectively in the cooling system.
4. If water temperature is high when the AC is turn on during summer time, most probably there are dirts attached on the surface of the condenser causing poor heat dissipation. Clean the condenser might be the best solution.
5. Water temperature sensor faulty can also cause the water temp alarm hence suggest to replace after checking.