my 2003 maxima has had the codes p0420 and p0430 come on simultaneously i read through post some say o2's others say pre cat .i know this car has 2 precats which would it be? if it were the 02s which would it be.only clear amswer i got from search was it is a very costly repair,btw my mpg sucks since those codes showed up and im worried about damaging my engine as some has claimed to do not sure if its true.Thanks for any help!

 

Mileage? It could be pre-cats and o2s. In a perfect world I would replace both depending on mileage. If it is just o2 sensors then you could replace both primaries and see how it goes. That will not be super expensive. Replacing precats is still recommended. In fact, I have no codes and wish I could afford to replace mine.

 

97k as of right now I did a visual inspection of the precat near the radiator and it is rusted to **** I was wondering if anyone with these codes fixed them

 

I would replace the o2's first for they are cheaper. PreCats + installation can get pricey.

Have you done anything to your car before getting the codes?

 

I changed the evap solenoid that's about it,I'm thinking of maybe gutting both and get de-foulers to pass emissions

Can i install defoulers without gutting cat?

 

 

I had both codes, I ended up buying an aftermarket Y pipe and bank 2 precat, along with replacing all the main O2 sensors. Is your car California or Federal emissions?

 

It's a 2003, there is no seperate Cali/Fed spec exhaust.

 

Thanks guys i bought my defoulers today plan on doing it this weekend will update its federal btw

Does anyone have a specific write up idk what im doing wrong 1.i have two defoulers for each o2 sensor my problem is when i thread one into the other it raises the o2 sensor on the precat to high so i cant get the sensor into the defouler with the little space between the defouler and motor

 

did you drill the one out?

 

http://vibrantperformance.com/catalo...sort=2a&page=2

 

yes i drilled one and screwed it into the other everything threads in fine its just not enough room to thread the o2 sensor

 

This. These are the ones to buy, not the cheap straight ones.
Also, putting non-foulers in is just masking a problem. That's fine if the O2 sensors are at fault, but if it's precats that are bad, you are only shooting yourself in the foot by not addressing it.

If you are just ignoring the problem, you might as well ignore the light, it's cheaper and easier, lol.

If the issue is the precats you should gut them out at a minimum. It's not good for the engine to have plugged/deteriorated precats, the engine will wear/fail prematurely.

 

Oh ok so the straight ones are just for the other cats ,i got the p0420 after using techron so i was thinking maybe the cat is clogged .I was thinking of trying cataclean

 

There is no cleaning them. They clog and disintegrate. Fuel additives just speed up by making them hotter.

 

its actually not a fuel additive according to their website

 

If you already know what you're doing then why ask?

 

Just needed some insight as to how others have dealt with this code

 

the non-foulers are supposed to be for the bungs after the precats.

 

Isally when you use some kind of "snake oil" in your fuel and you get a cat or o2 code after its due to the o2 sensor being on its way out.its usally so worn and dirty it can no longer hold it tolerances with the readings.

Sent from my iPhone using MaximaOrg

 

Gut both pre-cats and install the non-foulers. Issue will be solved and the car will run fine.

 

I have read many threads on the org of how people got rid of P0420 and P0430.