2015 Mazda 3 hatchback with 105k km. It's in perfect shape. Last night drove on a bumpy road. Parked for a few hours. Coming back there was a little rattle from the rear on every single bump large and small.

I tightened up the screw holding the spare jack. But didn't help. Today as I'm driving, the following happened in 5 seconds:

  • rattle suddenly became much more frequent and loud
  • then sounded like something fell off the car
  • I looked in rear view mirror, but didn't see anything fall out and surrounding cars didn't swerve or stop

I didn't have a chance to stop and see what fell off. Car behaves completely normal now. Brakes, suspension all fine.

I know question is super vague, but has this ever happened to anyone? What was the cause?

2 Answers 2


I see 3 major possibilities:

  1. Something stowed in the back of the car came loose when you hit a bump and was rattling around for awhile. It then found its way somewhere where it can't rattle anymore so you don't hear it
  2. A door or window mechanism came loose, you can determine this by testing the windows, handles and locks of all your doors. If something doesn't work that used to this is the likely culprit
  3. Something fell off your car. This could be a heat shield, some sort of linkage or any number of things. If it was meant to be attached there's a reason for it so you'd want to get it fixed

Once you've eliminated #2 I would approach this by taking everything out of the back of your car and seeing if you can find a likely cuplrit for #1. If you can reproduce your rattle then I'd consider it solved, if you can't find anything then take it to a mechanic for an inspection.

  • Thanks. Will do #2 first and check as best I can for #3
    – CarOwner
    Oct 4, 2021 at 11:57

Have it checked.

A broken part could have finally fallen off.

Unless you know what was there before you won’t know it is missing.

  • Thanks. I'll have it checked if I can't find reason
    – CarOwner
    Oct 4, 2021 at 11:58
  • Another possibility is that a heat shield or something else that was loose on the underside dislodged enough to stop rattling but not enough to fall completely out of the vehicle.
    – Jupiter
    Oct 4, 2021 at 12:28

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