[Daniel9]

I have a 2018 Volt with 5,600 miles. Since day one, when I move the shifter from Park to Reverse or Drive, I occasionally get a whirring/whining sound coming from the engine area. The sound only lasts for a second or so. It seems to happen more when the car is warmed up. No warning codes or lights. Any ideas?

 

[jcanoe]

I have a 2018 Volt with 5,600 miles. Since day one, when I move the shifter from Park to Reverse or Drive, I occasionally get a whirring/whining sound coming from the engine area. The sound only lasts for a second or so. It seems to happen more when the car is warmed up. No warning codes or lights. Any ideas?

It could be that the sound you hear is a coolant pump for the electronics or battery. It could also be the vacuum assist pump for the ABS power brakes.

 

[9G-man]

Do you set the parking brake? Could it be your electric parking brake releasing automatically? Otherwise i'd say brake vacuum accumulator pump.

 

[Norton]

It's power brakes. It has an accumulator. But there is NO Vacuum powered brake system on these, or most modern, cars.