2017~2021 Rear end noise I can’t chase down

Hey there everyone. I bought a 2017 GT about a year ago. Love the car however it seems to have developed a new noise that’s driving me crazy. Two months ago I noticed a popping/ knocking noise coming from the rear passenger side. It wasn’t all the time, but enough to pique my attention. I hear it mostly at low speeds, going over small bumps and dips in the driveway. When I had it serviced at Mazda the tech checked it out and said he couldn’t find anything wrong with the suspension, but heard what sounded like a noise in the trunk. Fast forward a month and the noise is worse. Brought it back and drove around with the tech who heard it and looked over the car before deciding it was a loose spare tire. Well it definitely isn’t. Noise is now near constant at low speeds on both sides. The tech had pushed on the plastic protective housing when looking the car over and it did sound similar, but I honestly can’t tell if that’s the issue. Plus I haven’t found a post from anyone complaining about it. Is it normal? Am I just nitpicking and being paranoid?
 
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2018 CX-5 Sport
Make sure the unused seat belts aren't making the noise, I had some noise going on at one point and it was the passenger seat belt. It is hard for the board members to diagnose because we can't hear the noise.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Hey there everyone. I bought a 2017 GT about a year ago. Love the car however it seems to have developed a new noise that’s driving me crazy. Two months ago I noticed a popping/ knocking noise coming from the rear passenger side. It wasn’t all the time, but enough to pique my attention. I hear it mostly at low speeds, going over small bumps and dips in the driveway. When I had it serviced at Mazda the tech checked it out and said he couldn’t find anything wrong with the suspension, but heard what sounded like a noise in the trunk. Fast forward a month and the noise is worse. Brought it back and drove around with the tech who heard it and looked over the car before deciding it was a loose spare tire. Well it definitely isn’t. Noise is now near constant at low speeds on both sides. The tech had pushed on the plastic protective housing when looking the car over and it did sound similar, but I honestly can’t tell if that’s the issue. Plus I haven’t found a post from anyone complaining about it. Is it normal? Am I just nitpicking and being paranoid?
There have been many reports about rattle noise from rear over bumps by loose rear liftgate spoiler, especially when some nuts have fallen down somewhere. You have to take the inner liftgate panels off and see if you have such problem.
 
Finally figured it out. Turned out to be the rear seats. Looks like the connection to the d-ring somehow got loose on both sides. Strange it happened on both sides, but hell, at least the noise is gone. I figure if it starts happening again I’ll just wrap a little tape around the connection point. Thanks for the help guys, and thanks for pointing me in the right direction. Had I not leaned on the edge of the seat checking the seatbelts who knows how much time I would’ve spent looking for that damn noise.
 
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