For the first time, I heard what sounds like an electric motor running after I turned the car off (2021 CLA250). The sound was emanating from the left-rear wheel well "area". I waited a couple of minutes, and it still kept running. I then started the engine, drove in reverse, then forward, then turned off the car. I did not hear the motor after that. Any ideas on what motor that would be (fuel pump, something to do with the brakes)?