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Jay, Certified Infiniti Technician
Category: Infiniti
Satisfied Customers: 20382
Experience:  20+years, Nissan and Infiniti experience and currently now working for a Infiniti Dealer
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Where is the bank 1 sensor located on a 2003 infiniti i35 i

Customer Question

Customer: where is the bank 1 sensor located on a 2003 infiniti i35 i have a p0420 and a p0302 is it the same location as i30
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Submitted: 1 year ago.
Category: Infiniti
Expert:  Jay replied 1 year ago.

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

Bank 1 is the side of the engine closest to the firewall. So the P0420 is a Bank 1 Catt Converter code. This means that the Catt Converter would need to be changed.

The other code P0302 is a cylinder misfire on cylinder number 2 which is right up front by the radiator side of the engine.

Did you change spark plugs or something on the car?

Customer: replied 1 year ago.
yeah and chaged all the boots that go on the spark plug. could it also be the 02 sensor that connects near the engine manifold ?
Expert:  Jay replied 1 year ago.

You get catt converter codes from 02 sensors working. It's a myth that 02 sensors cause catt codes. What happens is the front 02 sensor before the catt converter monitors the unconverted gases. Then the gases go through the catt converter and the rear 02 sensor verifies the gases have been converted properly. When the rear 02 sensor starts to have readings the same as the front 02 sensor it means that the catt converter is not converting exhaust gases properly and it sets the Catt code.

So you will need to replace the Catt converter to resolve that one code.

What brand spark plugs do you have installed in the car? Did you clear the codes after you did the coil boots?

Customer: replied 1 year ago.
No i didn't, bosh platinuim is spark plug type i used
Expert:  Jay replied 1 year ago.

Oh god.. That will cause it. Bosch Plugs are the worst plugs for these engines! Get rid of those plugs and put in NGK platinum plugs. These engines were designed to use NGK's. Any other plugs, especially bosch will cause misfire codes and running issues.

I would put NGK spark plugs in the car and clear all the codes. Then go from there. I will bet your misfire issue will stop, the thing we want to see if it will return is the Catt Code. If it does, then you will want to address it. If it doesn't then it could have been caused by the misfire code which was due to the type of plugs installed.

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.

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Thanks Jay!