[dayjaby]

Isnt something similar possible for cars? Based on certain frequencies in the motor area, you can deduce what is faulty?

[hoerensagen]

That is definitely done for bearing in ratting machinery. You can often even pinpoint which bearing is damaged and which part of that bearing is damaged, based on the frequency spectrum.

[janice1999]

There are several companies that use vibration and sound to detect faults (condition based monitoring). Otosense was one (now part of Analog Devices).

https://www.analog.com/en/lp/001/machine-health-sensing.html