Catalytic Converter and Exhaust Manifold... what's the scoop?

[porkandbeans]

Looking to buy new cats and I come up with conflicting options.
The far majority of my searches come up with parts that look like the bolt on footballs with flanges on both sides. (pretty standard looking cats)
But I had thought that our cats (FX45) were fixed to the exhaust manifold. And hence these were a complete biatch to remove and replace.
Looking under my car, I see the "easy" kind.
Do I also have the exhaust manifold one?
Do we have both?
Which gets replaced with the faulty cat codes? (I think they were P0420 & P0430)

 

[la_fx35]

Can't see any of your pictures, Pork.

The FX45 has two cats. One is attached to the manifold. The second one is attached to the end of the first one.
I replace both of mine last October.

Here is a picture of the one with the manifold.


Here is the second of is aftermarket. This is the one you see right under the car.

 

[porkandbeans]

Thanks Andy! That was exactly my question.
So with right and left side, I get to buy 4 cats. $$$$
It makes sense for me to replace the manifolds while the engine is out. Any idea if either the 1st or 2nd cat causes the P0420 and P0430 fault codes?

 

[skywalker999]

I think it's only 2 cats not 4

 

[la_fx35]

FX35: 2 cats.
FX45: 4 cats.

@Pork, most likely is the manifold cat that is causing those codes. I had the same code. I've been ignoring it and by the time I am ready to tackle the manifold cat, my secondary cat under the driver seat got a big hole in it.

Here is a picture of the inside of my manifold cat:


Here is secondary cat with big burnt out hole in it:


I recommend to replace the up stream (before the manifold cat) while you at it. It's a big PIA later if it fails.

 

[rammersFX]

Removing The primary cat will throw a code, the sensor is in between the 1st and 2nd cat.


Sent from my iPhone

 

[la_fx35]

The first O2 sensors is before the 1st cat.
The second O2 sensor is after the 1st cat. - corrected

 

[rammersFX]

I thought the second sensor was between cats 1 and 2.

To my knowledge, The design is like this to meet the CARB requirements, but for the other states where emissions are not required, the secondary sensors can be replaced by teat pipes (at least that set up was applicable on my previous Xterra)

I am curious now, will take a look over the weekend to confirm (I was thinking in removing the secondary cats).

Sent from my iPhone

 

[la_fx35]

@Rammer. My bad!!! You're right.
The second O2 sensor is in between the first and second cats.

 

[i_ride45]

@rammersFX did you ever look into removing your secondary cats? Just wondering cause I am thinking of doing the same thing. Since the sensor is before that one, it removing it should throw any codes, right?

 

[rammersFX]

It would not throw any codes, you should be able to do it. Check your state’e emissions laws before proceeding though.


Sent from my iPhone

 

[CBRworm]

I know this is an old thread, but the rear two cats are different depending on the year. My '06 45 rear cats are different dimensions from any of the direct fit options I have seen. And they are different than the ones shown in this thread.