A Positive Crankcase Ventilation (PCV) valve is a crucial component of any BMW's engine. It helps to regulate the pressure in the engine crankcase and prevents the buildup of harmful gases and pollutants. If the PCV valve fails, it can cause a variety of issues with your BMW's engine, including decreased performance and increased emissions. In this article, we'll explore the five signs and reasons for a BMW's PCV valve failure. Rough Idle One of the most common signs of a failed PCV valve in a BMW is a rough idle. This is because the PCV valve regulates the flow of air in the engine, and if it fails, it can cause an imbalance in the air-to-fuel ratio. This can result in a rough or uneven idle, which can be especially noticeable when the car is stopped or in neutral. Decreased Fuel Economy Another sign of a failed PCV valve in a BMW is decreased fuel economy. If the PCV valve is not func [...]