This is something that I’ve experienced. A rattling in the rear of the Y on rough roads. Not saying what I’m experiencing is what you are, but I’ll share my rattling. I removed everything from the rear of the car to make sure it wasn’t something else. Try this, open the rear gate, once it’s fully open rapidly move the gate up and down. I’ll bet the you’ll see movement on the left hinge with accompanying noise, I’ll assume that’s the noise you are hearing. The right hinge doesn’t have the same movement as the left side does. I had the service center look at it again today as they said that they had fixed it previously, there was some adjustment on the seam (no idea where). Today they checked other MY’s and said that it was normal! They were unable to tell me why one side would have that amount of “play”. Not super happy about the noise back there, my overactive OCD at work
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