039202400P (also Volkswagen Group OE number 04L965567 and Porsche OE number 9A7.965.567.00) is an auxiliary cooling water pump.

Although the car water pump has a simple structure, it is the power source for the engine cooling system and is crucial to the engine’s health. Understanding its function, working principle, and common faults helps car owners to identify potential problems in a timely manner and perform proper maintenance, thus avoiding major issues and protecting the expensive engine.