I just bought a 2002 E430 and heard a rattling noise coming from around the front wheels or axle. As it was still under warranty, I took it back to the dealer where I bought it and had it checked -- turned out it was the catalytic converters, which they replaced. When I asked what had caused the failure, I was told that Mercedes had a "bad batch" of cats from that year, and that the new ones were an updated/improved version.

Is that true? or is this dealer giving me the run-around??? I know that there are other potential causes, but if anyone has heard of this problem with E-class cars from that time frame, I'd like to know.

Thanks.