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Honda-Man, Honda Mechanic
Category: Honda
Satisfied Customers: 3113
Experience:  I have an Associates Degree in Automotive. 10 Years experience on all makes and models. 20 Years Honda only including factory training. Over 30 years total.
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I have a 2001 EX Civic I had P0420, I changed my. I am

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I have a 2001 EX Civic I had P0420, I changed my
JA: Are you fixing your Civic yourself? What have you tried so far?
Customer: yes I am trying to fix it myself, but I changed my 02 down stream sensor, cleared my check engine light. Now I have this other issue were this happened to me once months ago. Now it happened more frequently. When ever I try to accelerate, it looses power, high RPM in shifting gears and it sounds like misfire or air leakage sound when flouring it. I don't have a check engine light on . Spark plugs were changed about a year go, I put new coils this past weekend and still I can figure it out. I have asked around they mention maybe the Catalyst convertor or a gasket leak. Thanks for the help.
JA: Does the light stay on, or does it blink?
Customer: I don't have a check engine light anymore after I changed the downstream O2 sensor.
JA: Anything else you want the mechanic to know before I connect you?
Customer: No, that all I got.

Thank you for taking time to seek expert Honda advice. I am reviewing your question and gathering information. Please standby.

DTC P0420: Catalyst System Efficiency Below Threshold. This code is pretty much 99.9% a bad catalytic converter. It sounds like it may have came apart inside. It can fail in a way to restrict the exhaust flow. Have you replaced the converter?

Customer: replied 1 month ago.
No I have not replaced it yet.

I have seen this code on many Civic'c it's fairly common. I would replace the converter. Would you like a price and Honda part number?

Is your EX a coupe, sedan AT or manual trans?

Customer: replied 1 month ago.
sure, thanks. I will order one and replace it.
Customer: replied 1 month ago.
EX Coupe, AT.

Thanks be right back.

Honda-Man and 2 other Honda Specialists are ready to help you

Online info for Honda part click HERE.

Click HERE for a price from O'reilly auto parts.

I think for the price difference the MagnaFlow is the best option. But it won't last as long as the Honda part. Guess it depends on how long you plan to own your Civic.

Thank you, ***** ***** have any other questions on this subject just ask!

Honda-Man aka Cliff