Rattle From Beneath Vehicle on Mercedes-Benz CLK55 AMG

Problem Description and Possible Solution

When the engine is running, but the vehicle is not moving, a rattle heard from beneath the vehicle could indicate that one of the exhaust catalytic converters has failed. The substrate (the internal part of the catalyst that reduces emissions) can loosen and bounce around inside the canister section of the converter—the defective unit will need to be replaced. If this problem is ignored, the substrate can break down and reduce to a size that plugs the outlet pipe, which will cause a sudden loss in power.

Problem Data
RepairPal Verified
Average mileage: (–)
2 model years affected: 2001, 2002
2 people reported this problem