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Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 20255
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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I have a 2006 nissan altima with a service engine soon

Customer Question

hello i have a 2006 nissan altima with a service engine soon indicator. i pulled the codes and pulled p0420. the cars and drives awesome. i check fatalist and found that rear oxygen sensor wasn't doing anything it seems stuck at .340 vdc so makes me believe that isn't the catalytic converter instead a bad sensor. engine size is the 4 cylinder. no exhaust leaks etc. like i said no performance issues at all.
Submitted: 1 year ago.
Category: Nissan
Expert:  Super mechanic replied 1 year ago.

Hello and welcome. My name is ***** ***** you for visiting the site, I will be happy to assist you today.


Let me just say that any money that you paid, or if you have a subscription, that money stays in your account until the answers are rated, (positive) regardless of how fast or how long it may take to get finished. You can FOLLOW UP AT ANYTIME, even after rating.


That does sound like it is just a bad 02 sensor.

If you give me your email address, I can get the test instructions for it and put it in a PDF file, (it is rather large) and send it to your email address for as little as possible.


You will just have to accept the additional service offer and ENTER your email address in the “ENTER CONTACT INFO” section so that I can see it, Thanks

Expert:  Jay replied 1 year ago.

Hello my name is ***** ***** thank you for your question.

When you get a P0420 or a P0430 code it is NOT a 02 sensor issue. On these cars for a Catt Code to be triggered, the rear 02 sensor would mimic readings of a front 02 sensor. When the computer see's the rear 02 sensor mimicking the front that means that the Catt Converter is not converting exhaust gases properly and sets the Catt Code.

If you have any more questions on this, please feel free to ask.

If not, and you're satisfied with my help, please Rate me. That is how I get credit for my work.

I hope I have provided you with Excellent Service.

Thanks Jay!

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