The flex-pipe just before the Cat is a little rusted through and is definitely leaking fumes. Originally thought this was the problem. Have to cut and weld in new flex pipe. But the loud rattling is actually coming from the Cat it seems, and I have tried pressing on the Cat housing with a rag but that does nothing to reduce the noise, so I am thinking it is the Cat itself.
I don't care much if the Cat doesn't work, but why would it rattle?
Read more: 2000 Honda Accord LX rattling catalytic converter: Diagnosis?
