Hi everyone,

I recently purchased a pre-owned 2024 W206 C300 4MATIC sedan with only 12,000 km. While the car is great, I’m dealing with two distinct rattle issues that are driving me crazy.

1. Interior Rattle from the Right Side When driving on rough roads, there’s a plastic-on-plastic hitting noise coming from the right side.

• Key Clue: The noise disappears or becomes significantly quieter when a passenger is sitting in the rear right seat.
  
• Suspected Areas: I suspect the the rear right seat side bolster. When I tap these areas by hand while parked, they produce a similar sound.
  

2. Trunk Noise (When Rear Seats are Folded) When I fold the rear seats down to carry long items, I hear a severe noise from the trunk.

• The Sound: It sounds like something is rolling or sliding on a metal sheet, especially during deceleration.
  
• Observation: Interestingly, when the seats are upright and locked, I can barely hear this "rolling" sound. I’m not sure if this is related to the first issue or if it's a separate problem.
  

I want to try some DIY fixes. Could anyone provide advice or a disassembly guide for the rear side bolsters and the trunk trim? Also, if anyone has experienced those noises, I’d love to hear your solution.

Thanks in advance for your help!

 

Do you have something stored under the trunk floor?

 

I don’t have anything under the trunk floor.