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[Solved] P0420


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2007 Honda Civic Hybrid Sedan 4D (Silver) -255,700 miles- has P0420.


I have never bought a car in my life and I bought this one just 10 days ago with the check engine light on. Apart from having to spend $35 to remove the rusty exhaust cover that was making weird noises after I scraped the bottom, I haven’t had to spend any money on it for mechanical reasons. And $35 was certainly too expensive for that 10 min labor, in my opinion. After that, I decided to get a $27 OBD2 scanner from Walmart and found that it was p0420. I erased the code while experimenting with the scanner. Having not had driven much in the past, I scraped the bottom again 2 days ago a and the check engine light came right back on. I have driven close to 300 miles since. The car continues to work just fine. No irregular noises that I (a rookie owner) am aware of. My research has showed me that it could be issues with leaks in the exhaust or oxygen sensors or catalytic converter(s). Should I do anything about it? 

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2 Answers

First make sure that you don't have leak in the exhaust system. Then scan it and find out about the health of the down stream oxygen sensor. If it checks out, you may have issues with the cat. Scotty has a video on how to clean it. Hope this helps. Btw, if you don't need the inspection in your area, leave it alone. 

Thank you.

You're welcome. Keep us posted.


Why do you keep scraping the bottom of your car?  Are you addicted to speed bumps?


Haha. Haven’t done it for about 400 miles now. I guess the addiction is fading away.