Why would an OEM catalytic converter from a 99 Civic Si with 45K on it go bad? The insides are very clean, no black carbon buildup or soot, it's just that the inside "honeycomb" has completely fallen apart causing exhaust flow to be completely blocked. I'm not sure what would cause this. Any ideas? Thanks.

 

they're supposed to last longer than that... leaded gas can destroy cats.

 

FYI - Honda covers these under an 80K mile warranty, in case you weren't aware. At least that's what my dealership told me ...

 

lol federal law makes them supposed to last at least 50k miles.. dunno what happened to yours.