Installed two other brand cats on an ML320 10 months ago and they are already making rattling noises ... supplier says they must be getting too much unburned fuel to do that so soon ?! If fuel burn is too rich, would not an Engine Check Light come on to indicate that there is a problem?? No light and no codes are present. Someone please advise ... thanks, Ben Carter

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Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)