Car inspection and I didn't pass because of code P0420?

  • 120,100 MILES
I live in Texas and I would like to know if it's okay to replace my catalyst converter with an universal one- I'm not sure if it's legal or okay? Two places I called they told me I need to ask my mechanic if my Nissan Sentra 2008 is compatible. I recently went to get a car inspection and I didn't pass because of code P0420 - Catalyst System Efficiency. Lately, my car dies, stalls or loses power. Do you think this may be causing the problem. I don't have a lot of money to fix this problem but I don't want to have to spend more money in the long run. What are your recommendations? Thanks
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Wednesday, July 3rd, 2013 AT 8:03 AM

1 Reply


When replacing a catalytic converter, it is best to replace it with a direct fit compatible part. That way you can be sure it will do the job exactly as the factory unit did and it will be road legal.
Keep in mind that the code P0420 can get triggered due to other issues than the catalytic converter. So, it is important to figure out what is the actual cause before replacing any part.
So, if the issue is not the converter, replacing it will not fix the problem.
As this code can be triggered due to bad fuel injector, leak in the air intake tube, improper ignition timing etc.

Also, you mentioned the vehicle stalls or losses power, which may or may not be due to a clogged catalytic converter.

So best course of action would be to take a step-by-step trouble shooting method and that can help determine the issue.

I have attached the trouble shooting guide for the P0420 code below.

Please let me know of any questions.
Thank you.
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Sunday, January 9th, 2022 AT 9:09 PM

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