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2001 Accord P0420 CEL code - not P0459

Old 09-17-2012, 07:14 PM
poorman212's Avatar
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Join Date: May 2010
Location: Youngsville, NC
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Have to agree with Redbull-1 here. With the car "cold", crank it up and "feel" around the exhaust for leaks, it any are found then address them before going any further with other repairs.

PS- buy the wife her own Honda . My wife has the Pilot, she came home Saturday afternoon and I noticed the undertray "looked funny" on the drivers side....upon closer inspection there are clips and pieces of the tray missing....I did the dumb thing and asked what she hit or ran over.....should have just bought the parts and been done with it.
Old 09-19-2012, 10:30 AM
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Join Date: May 2007
Posts: 135


I decided to try the SeaFoam method of exhaust leak identification. Sure enough the flex pipe looked like a nuclear power plant steam tower, smoke shooting through all the threads.

I've heard differing opinions on the cut out the flex pipe vs. replace the whole thing. Since my Accord as the section of pipe from the manifold to the cat that contains the flex pipe and can be taken out in just that section I'm more inclined to do that. I can get the part from a reputable parts dealer (FCP Import - I use their FCP Euro site to get stuff for my 1993 Volvo 240 Wagon, they have some good hard to find parts) for $92 and free shipping, seems like a no brainer to me.

Two questions though, what are the gaskets for the pipe connecting to the manifold and then the section to the cat? I see in the diagram that it looks like just an O ring type thing but then I see a different looking actual gasket.

Secondly, the bolts are probably going to be a bitch to get off, where to get replacements? Are they special automotive or just an exact match from anywhere will work?

At least I have something to do with 4 days off next week lol
Old 09-20-2012, 06:10 PM
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Join Date: May 2010
Location: Youngsville, NC
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Not sure but I think the ULEV is different -pipe and gaskests - that the regular.

Some of the gaskets are metal rings.

If the bolts have to be replaced, suggest grade 8 bolts of the proper size and length from where ever you can get them. Getting the old ones out of the cat will be fun.
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