If your car makes a whistling sound when it is idling, you may have a vacuum hose that is damaged or leaking. And while it may not necessarily disappear when you begin driving, it may become more difficult to hear as the RPMs increase.
However, if there are no other symptoms, it could be a faulty water pump. This is especially true if the noise is louder than usual and emanates from the engine compartment. If this is the case, it is preferable to have a specialist examine it.
A faulty air filter, air intake hose, or alternator belt could be the source of the noise in some circumstances. Check for cracks, tears, and other indicators of damage by looking beneath the hood of the vehicle. If so, you should replace the component as soon as feasible.
The noise could potentially be the result of a malfunctioning exhaust system. In this situation, you should inspect the pipes and muffler for corrosion or signs of wear and tear. If so, it is preferable to have a professional examine it and replace the faulty component.
Overall, a whistling sound when your automobile is idle could be a sign of a more serious problem. It is usually advisable to have it examined by a specialist as soon as possible.