Volvo's idle speed goes up and down, and it keeps complaining.

The throttle or air flow meter is out of order. The whine of Volvo idling is caused by the unstable intake of the engine. The common reason is that the throttle valve or air flow meter fails, which leads to unstable intake of the engine, unstable idle speed and abnormal noise. Throttle is an element to control the intake of engine, which consists of two forms: stroke control valve and electronic throttle.