# P2A00 SES - Replaced front O2 Sensor and Installed New Header



## davidpaul17 (Jun 1, 2011)

About 1 year ago I was getting the p0420 so I installed a header - everything was great for the first 3k miles - then I got the p2a00 code - which is supposedly a bank 1 o2 sensor - I replaced it but am still getting the code - 
I have read that the MAF may need to be replaced??

Any help is appreciated!


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## 96v6camaro (May 25, 2010)

Looks like a lot of things can affect that. Have you checked for exhaust leaks? I did a little reading on the code and a lot of people have replaced a lot of o2 sensors getting no where. Which one specifically did you replace? I know a clogged CAT can wreak havoc on o2 sensor readings as well.


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## davidpaul17 (Jun 1, 2011)

Thanks for the response - I replaced the front o2 sensor - I have not checked for exhaust leaks - what is the best way to do that?


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## 96v6camaro (May 25, 2010)

That code may pertain to the rear o2 sensor - the two can get set each other off if one is new and one is old. However I would still look for exhaust leaks as o2 sensors are expensive. As I've never done that I did a quick search and found a few methods. One is a smoke machine that shops use to flood the exhaust and see where leaks out. Probably out for you. Another is to feel along for any air around the exhaust (probably best done when everything is cool to start - figure out areas you want to check before you do it). You can also sort of force your own smoke test by running seafoam into the intake as it smokes quite a bit once you start the car back up and it burns it off making leaks easier to visually identify. I suppose you could also try soapy water on a cool car around junctions and gaskets but personally I would feel for it and maybe do the smoke test. I read somewhere someone suggested increasing exhaust back pressure with a rag in the tailpipe to force more exhaust out the leak if there is one.


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## davidpaul17 (Jun 1, 2011)

great - thanks again and i will try some of what you suggested


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## 06FrontierRookie (Jun 24, 2016)

so what was the final result. I have having the same problem on my 2006 Nissan Frontier. I replaced the o2 sensor and the Catalytic Converter about 1 year ago and now that it has gotten hotter outside the code is a new one it went from the original code of a P0420 to a P2a00 now. This is driving me up the wall so before I start throwing parts at it I was wondering what it could be now. I don't want the new cat to bad already. I have heard about the MAF sensor maybe. An exhaust leak, a intake leak or a bad 02 sensor again at the top of the cat. so what is really goin on I am so upset with this and if I don't get a handle on it I am going to just load the ruck up with TNT and watch it explode like a cartoon. Please some one help me out with this. It goes to the shop tomorrow but I have already reset the code and I will have to explain to the shop what the cod was that I found. No I have checked on Nissan's web site and it also said it could be fuel pressure, intake, or a bad sensor. But like I said a lot of people say it could be many other things. Now I have put jut regular 87 fuel all the time at a place that's sells it the cheapest in town don't know it that could cause it to go also. SO now everyone knows how confusing this code is and a lot of shops I called don't een have it show up on their systems.


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