What is the reason for the BMW 5 Series indicating insufficient coolant?

[PenelopeLee]

It is due to a lack of coolant in the radiator. It should be replenished promptly. Coolant is an essential part of a car's engine, composed of water, antifreeze, and additives. It circulates within the engine's cooling system, carrying away excess heat generated during engine operation to ensure the engine runs at a normal working temperature. During high temperatures, if the concentration and level of the coolant are not within the normal range, it can easily lead to engine failure or even overheating. When using antifreeze, please note the following: 1. Try to use the same brand of antifreeze: Different brands of antifreeze may have varying production formulas. If mixed, chemical reactions between additives may occur, rendering them ineffective. 2. Expiration date: Most antifreeze has a shelf life of two years (some products may last longer), so ensure the product is within its expiration date when adding. 3. Regular replacement is necessary: Generally, replace the coolant every two years or every 40,000 kilometers driven, with taxis requiring more frequent changes. When replacing, drain all the old fluid, clean the cooling system thoroughly, and then add new fluid. Do not dilute it with water.