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2014 Elantra P0420 Code

1235 Views 6 Replies 4 Participants Last post by  Propflux01
Hey all!

If this is in the wrong forum, let me know so I can repost.

Bought a 14 Elantra 1.8 new. Currently has 113,000 miles. Never a single problem until recently.

Check engine came on, had the code read and it was a P0420 and it seems the Catalytic Conv. may need to be replaced.

The couple quotes I have had are super high (1500-1800) to change the O2 and Cat out.

Anyone have any experience doing this work? Everything accessible with the right tools?

Have googled this every way I can imagine to see if a video can show me and I can’t find a thing.

Any help is appreciated!!
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Before changing your CAT converter, I would try the anti fouler trick placed on your post O2 sensor. This should fix your P0420 code and stretch the service life of your CAT. Lots of info on the matter. Its a cheap fix that works. I have it on my '99 Odyssey @225K with original CAT. Been passing smog for several years now. Good luck.
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Didn't even know that was a thing. I will certainly look into it. Thank you for the help.
Before you change the cat, change the O2 behind it and put a bung extender on it.
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Before you change the cat, change the O2 behind it and put a bung extender on it.
It isn't just a code. Also having some performance issues. Not shifting quickly, slow acceleration, taking a long time to get to 60. Would this fix the problem as well?
P0420 has no effect on engine performance. It sounds like there may be other issues. One cause of cat failure is them getting clogged up. This is from misfires usually and there is not much you can do but replace the cat. If I were you I would look for a used one on ebay with 50k miles or so on it.

If you have an ODB data reader look at the 2nd O2 voltage. It should be above .600v or so and stay there for a good cat when at highway speeds. If it's swinging up and down a lot or below .600v then it's not doing the job or the O2 is bad.
Your symptoms sound exactly like a toasted converter.
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