After washing the car, the engine speed of Volkswagen polo car is as high as 4000 rpm. What is the reason for the loud noise?

Hello, according to your description, the throttle should be dirty and the adaptive value of taxi idle speed has changed. It is recommended to check whether the throttle is dirty and whether there is a vacuum tube leaking. I hope my answer can be helpful to your car problem, please consult the car master. 4S shop professional technician, 10 minutes to solve.