[daepp]

Finally got my Check Engine Light code diagnosed, and as I feared it was PO-42 - catalytic converter not working well enough. It's a MBZ SUV with 200K+ miles.

One cat from MBZ is $640 - parts only. A local muffler shop my company does business with thinks they can replace both cats for around $700 - but they will not be oem. They say it will take care of CEL and that both should be replaced.

I can hear what sounds like a rattle or marbles coming from the drivers side cat.

I think in CA now you are supposed to just use the oem part, but if my emissions are fine and the CEL is taken care of, why not go aftermarket?