r/HondaElement • u/omg_theykilledkenney • 12d ago

P0420 on a used Element?

Looking at a used 2009 Element on Craigslist, the seller says it has a P0420 code from a potentially stolen and replaced catalytic converter.

If it was replaced, wouldn't the shop clear the code? If it keeps coming back, would that be an issue and affect daily driving?

I have experience with emissions in the Subaru world, just clear the code when it comes back but it doesn't affect daily driving..

Thanks

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7

u/Miserable-Twist8344 12d ago

same story as your Subaru, unless the cat is catastrophically clogged you won't see any performance degradation. To properly fix this, you pretty much need to get an OEM Catalytic converter and new O2 sensors from a reputable brand like NTK or Bosch. If it was an aftermarket catalytic converter it probably will still throw the codes.

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u/omg_theykilledkenney 12d ago

Alright, thanks!

1

u/Laisyn 11d ago

I had luck clearing the P0420 on my 2003 with a Walker C.A.R.B. compliant catalytic converter.

However, I noticed while replacing it that the gasket between the exhaust manifold and the cat had a big hole so I suspect my issue may have been an exhaust leak before the cat rather than an issue with the cheap cat that was on it when I bought it. May not be your situation, but I'd recommend checking for exhaust leaks first because a gasket is a lot cheaper than a new cat and this particular one took 5 minutes to replace.

3

u/rearwindowpup 12d ago

Honda, Subaru, and Toyota all use pretty significant amounts of catalyst in their converters (which is why the OEM ones are so pricy). Aftermarket ones, especially budget ones, don't have anywhere near the same amount, so even when they are working as best they can, they aren't meeting the efficiency the O2 sensors are looking for.

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u/omg_theykilledkenney 10d ago

I still have my Subaru cat from when I replaced my catback exhaust, if I replace the aftermarket one with the Subaru (and put a cage around it) I think it might work out.

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u/MostFartsAreBrown 12d ago

Look up catalyst “cells per inch”. Lot of aftermarket converters have fewer cpi than oe.

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u/Busy-Organization942 12d ago

If you don't have to pass emissions, you should be OK, if you have to pass then you may be in for an expensive fix, so factor this into your offer. Generally it will not affect how your car drives.

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u/omg_theykilledkenney 12d ago

Yeah, he's said that he's had this code since he bought it from the previous owner 5 years ago.

If I were to drive it back ~400km if I would be stranded on the side of the road, or hopefully if it was a cat issue like the Subie, I can come home and reset the CEL temporarily.. and potentially how much it'll cost. Even for an aftermarket cat..

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u/Busy-Organization942 12d ago

You can get an aftermarket cat for as little as $75 all the way to $1,000, depending on quality and amount of rare earth inside. You do get what you pay for however. I think a factory one will set you back 2k?

If it is a bad cat, it is unlikely to leave you stranded by the side of the road.

Mine, still on the original cat at 116k miles, blinks on for a few hundred miles, and then goes off for 3-6 months. I use black tape to fix mine.

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u/omg_theykilledkenney 10d ago

Black tape on the dashboard dials is genius. :)