Oxygen sensor/Cat

[Kit]

My 2002 with 162K has had an intermittent CEL for close to two years from the P0420 code. It would come on for a week or two, then go off for a week or two, but more recently it has been on more than off, so I finally decided to try to fix it. A Honda mechanic told me it was most likely one or both of the oxygen sensors because cats hardly ever go bad on Hondas. I have driven a number of cars beyond the 200K range, and two of them were Civics that I ran to 282K and 285K without ever having to replace an oxygen sensor or cat. Since I took the word of the mechanic about the cat, I replaced the downstream oxygen sensor a week ago with a new NTK. The CEL went out a couple of days later for part of the day, then came back on. A friend is telling me the cat needs to be replaced.

The big question about replacing the cat is whether the ones on eBay in the $125-150 range will work. Every one of those I have checked says it is not legal in CA, meaning it is a 49 state part. There are some that seem to be 50 state parts because they don't say they can't be used in CA, but they also cost a lot more. I don't live in CA so that isn't a problem, but my friend told me the computer in the car is set for 50 state specs, so if I may still end up with the CEL if I put a on 49 state cat. Can anyone offer any advice?

[Rasy]

Aftermarket catalytic converters tend to work for a short period. Anywhere from 6 months to a few years. The reason why the Honda ones cost so much is because of the greater amounts of platinum and rhodium to help break down the emissions.

I believe you can get away with using a 49-state cat, I have and it works fine (Random Technology hi-flow version) especially if you don't live in CA. The life cycle of the part won't last as long as an OEM one though.

[Grookes]

2002 with about the same mileage, very similar symptoms. Living in CA, it's an expen$ive problem. Sorry to hear replacing the sensor didn't work; I was about to push my mechanic on that. 2 different trusted mechanics have told me I need a new cat... worth it for a 14 year old car? Hmmm...

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[dirtyduck17]

Not to rub it in, but feeling very glad I live in a state with no emissions checks. Sorry for your troubles guys.

I will tell you that it has been my experience that unless your buying top shelf aftermarket parts the OEM stuff gets better results. I've been slinging wrenches on Hondas for almost 10 years now and I have seen the difference in the performance of OEM v. Good aftermarket. Also, there is a software update available for EP3 with recurring DTC P0134. It can help keep the CEL off. It's worth a try.

As for me, it's time for a test pipe and $150 bucks from the scrap guy.


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[Grookes]

Software update sounds like my last hope. Gonna have my guy check at the next oil change. I'm not feeling a $1500 repair on a $2000 car.

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[tommy]

I've had a Magnaflow on my 04 for several months now. I had one on my previous DD for at least 5 years, and a Random on my CRX for at least double that. So I've personally not had any experience nor have I really heard before about aftermarket cats being inferior to OEM ones. Honda charges more because simply it can.

[dirtyduck17]

I've had a Magnaflow on my 04 for several months now. I had one on my previous DD for at least 5 years, and a Random on my CRX for at least double that. So I've personally not had any experience nor have I really heard before about aftermarket cats being inferior to OEM ones. Honda charges more because simply it can.

You buy a cheap cat you get a cheap cat. I was referring to folks buying a/f sensors and oxygen sensors. Thankfully I live in South Carolina and with no state inspection laws I can run just about exhaust I please. It sucks having to drop $1100-$1400 bucks on a cat is a huge burden. I like to judge a cats true value by how much the scrap guys pay for the used cat. Most scrap guys will pay $120-$150 the cat, making the the cost of the cat more realistic. The cats from a V6 Honda only get $40-$50 bucks.

I do want to ask about the manga flow exhaust though. How is it? Sound? Performance? Good quality? I'd really like to hear your thoughts.

[tommy]

Sorry, it's the MF cat only. I did order the full catback exhaust on Friday, though, from Magnaflow (through Amazon - everyone has exactly the same price to the penny, though, and Amazon had free shipping, so they won). I had done the Megan midpipe at the same time as the cat, so that will be removed, since you can only by the MF exhaust from the cat back, not just the axleback piece for some reason, and I might as well throw on the new midpipe from Magnaflow as well.
I should have some opinions on the MF exhaust mid-next week, if all things go as planned.

[patrickvertigo]

I have the same intermittent cel. 170k miles on the car. If you are going to go with an aftermarket cat. Bosal has a pretty good replacement. Not quite OEM of course. Bosal part number 0991107. $159.79 on rockauto.com. This is likely the route I will go being I'm not in California. Amazon also has it pretty cheap. While comparing the inner portions of the cat to other replacement options, it does look better than most.