There comes some abnormal hollow sound like soft Karr Karr while I'm reversing my Honda City (2018) from last 4-5 days. Otherwise there is no problem. What can be the reason?
I think its normal. This sound should be arising only on low revs while reversing. If you reverse at relatively high revs (like 1500 or more) then the sound might disappear. Try it!
This sound is different from normal karr karr sound when the car in low revolutions. Its hollow and seems like arising from hollow long cylinder.
Is it continuous or cyclic in nature? I mean it becomes loud then become low pitched in cycles or its continuous. I was also experiencing some uncomfortable kur kurr sounds from (probably) gearbox of my city but came to know that it was normal as my brother's city had same sound.
One more suggestion, as you got your car in 2018 it is under warranty. Get it checked by the dealership. Although they will try to convince you that its normal, yet try it.
