I have a 2007 Honda Accord, manual transmission with 85,000 miles on it. I purchased this car brand new in 2007. My check engine light has been going on and off sporadically for about a month. I took it to Honda dealer and they found code P0420 Faulty Catalytic converter....They want $950 to fix it and it's not covered under the extended warranty that I purchased when I bought the car. I can't believe that a car with less than 100,000 miles and is only 6 years old needs a new catalytic converter. As I read through these threads, I'm not sure if I should have oxygen sensor replaced first or try to use cleaner. Another issue I've had with this car since I purchased it is that it uses a quart of oil in between oil changes. I have taken the car to the dealer several times about this issue and they state that it is "normal consumption". Would that have anything to do with a faulty convertor now? Help!

 

Hi Member...
I looked in my books and that code can also be caused by an Engine missfire running condition and also from a large vacume leak also Your engine oil leakage going into your exhaust-valve guide seals or piston rings.

That besides the Catalytic converter being defective. Testing the cat to see if it's bad is the 1st step.

WheelBrokerAng

 

Hey there, I'm not totally sure how similar the 2007 is to my 2001 but the link below is to a thread I posted awhile back when I got that P0420 code.

Mine ended up being a combination, but first thing to do is look for leaks especially right before the cat. Mine was leaking at the flex pipe and at the joint between the down pipe and the cat. The cat ended up going bad as well (you will see the pics). Tap on the cat and if you hear it rattle, time to replace.

Check out the post, it might guide you to diagnosing before sinking $$$$ into it. $950 to replace the cat when it might not be the issue is a bit much. A decent after market cat you can get under $200 and recycle the old one to defray the cost. 6 bolts and it's in.

https://www.hondaaccordforum.com/for...de-pics-50458/

 

There you are..better post with even more information for all to see.
Thank You! for finding that link in the forum..