I have a 98 DX with a small crack in the exhaust manifold. I purchased a used manifold off a 2000 Civic and was preparing to install it. A mechanic friend told me not to do it as the cat had been sitting and the chemicals in the cat may no longer be good. He said it would likely turn on the CEL. He said I would need to purchase a new one to avoid it triggering the CEL. IS HE CRAZY?

 

The chemicals in the cat, huh? There are no chemicals; just different metals. I say you'll be fine; the only problem I see is if the old owner of the manifold started melting the cats (unlikely, but with how some people run their cars, not impossible) or if the cat is clogged.

And do me a favor. Go backhand your mechanic for saying "chemicals" talking about what's in a cat for me.

 

Yeah, as Reaper says, just install the manifold/cat and hope it doesn't throw code P0420.

 

My 96 CX hatch had the bad luck of cracking right where the upper O2 sensor sits.
Turns out Honda had extended the warranty for a maximum of 10 years but I missed by 6 months.

No worries as I found a "mint" cat at a local high end recycler for $125.00 from a 99 h-back. A new gasket and replacement springs for the flex fitting and I was good to go.
No issues what so ever.

Huumm, I wonder how many people come in for a bad upper O2 sensor and leave with a new cat. convertor?

You'll be fine.

 

This Emissions Warranty stemmed from a lawsuit and was extended to 15 years or 150K miles. My 97 Civic is still covered.

 

^yeah, the cat has precious metals in it, Paladium or platinum or something,not chemicals. Thats why they are so expensive. I think your mechanic just wanted more money out of you. If you have a manifold with the cat attached, I dont think you can look, but if you have an EX cat that goes underneath the car, You can look through it and tell if it is bad by looking at the honeycomb to see if any of it looks melted.

 

Thanks folks. Eric, it looks like mine cracked right about in the same place as yours. Unfortunately, I am not covered by warranty (over 150.000 miles). The used manifold and cat that I purchased came off of a 2000 DX. I am planning to install it, gasket, bolts/springs and hope like you that I have no problems. I think the mechanic I took it to was behind on his boat payment or something. Thanks again for your responses.