Hi Guys,
I picked up my new 2017 340ix 2 weeks ago and it's making a knocking noise from the undercarriage when the fuel tank is below 1/4 full. (I know that most people don't recommend running with so little gas in the tank but there are times when I am not near a gas station.)
I noticed there are NO drivability issues. No Check Engine lights. Engine RPMs are stable. I hear it while stopped in Drive or when the car is in Park. I can hear it slightly as I am coasting very slowly also. So it's NOT the drivetrain. It's clearly from the exhaust or the cats. Here's my a video that I shot of the noise.
As I googled this issue, I also found another 340i that had the same issue. Another viewer of this video also chimed in and said his car had the same issue and the dealer said it's related to the cats "cooling off". The poster said that his noise also occurred with the tank below 1/4 tank as well.
Does anyone here have this issue? If so, did you ever get it resolved?