What is the reason for the flashing red R light in Sinotruk?

[MacWeston]

This red R is a water level warning light, indicating an alarm for low water level in the expansion tank. Simply add some coolant to resolve the issue. The main functions of coolant are: during cold winter parking, it prevents the cooling liquid from freezing and cracking the radiator or damaging the engine cylinder block or head, while in high summer temperatures, it effectively prevents boiling, avoiding overheating. The specific functions of coolant are introduced below: 1. Multiple functions: Used in cooling systems of automobiles, train diesel locomotives, tractors, ships, engines, radiators, and various mechanical equipment, diesel and gasoline engines, etc., it has multiple functions such as antifreeze, anti-boil, anti-corrosion, and anti-scale. 2. Descaling: Made with distilled water and added with anti-scale additives, it not only prevents scale but also has descaling capabilities.