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
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1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
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If you installed "aftermarket" cats then he COULD be correct. Not only the O2 sensors cause failure but also the air mass sensor.

MOST aftermarket cats WON'T take the punishment that OE ones are designed to take. 1996 & later cars need OE quality cats!

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