Hi all, PO432 signifies my cat needs replacement. Already changed the O2 sensors and installed a Borla exhaust system. Im also getting multiple misfires from all cylinders. I made sure my coil rail is plugged in tight too as my XJ is a 2001. Could a malfunctioned cat cause this? Also if the cat is bad, couldn’t I gut out the internals preventing clogged flow or a CEL will still be triggered?

 

My 2000 XJ sets that code, but only after a high speed run for over 30 minutes. I don't have the underbody converter on it anymore so I'm thinking it needs the backpressure from it for the converters to function properly.

Actually that code is showing the downstream 02 sensor on bank 1 isn't working or showing that converter isn't efficient. Try changing that sensor. Maybe the connection is bad.

You're going to need functioning converters to pass NY inspection anyway. I'd try a set from the boneyard before I bought new ones.

 

While we're on the subject my wifes 2001 throws the same code occasionally but I'm not sure how to decide if the cat or O2 sensors should be checked/replaced first. I have what I believe to be freeze frame data from my scanner, if that could help the diagnoses.

Any help would be much appreciated, let me know if you need the freeze frame.

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PO432 is saying the pre-cat on bank 2 is bad. I dont think it would be the o2 sensor because I changed all four already maybe 6-7 months ago. Ill check my connections tomorrow to make sure a wire didnt melt or something. The car idles pretty solid even with this code present and a needed head gasket replacement.
Unfortunately I in fact need an inspection and of course cannot pass until this is solved.

 

I went through this a few years ago on my '00 with CA Emissions.

It happened right after I changed out all 4 O2 sensors.
Which might have been a mistake on my part. Wasn't having any problems with them.
Just figured they had 150K on them and needed to go.

So my little theory is this.
One or more of the O2 sensors while not bad was not running quite as it should.
Good enough to not throw a CEL but not good enough to actually detect that the cat was not operating quite as it should.
So I put in brand new properly operating O2 sensors. Now they detect the quite not operating as it should cat.

If I recall correctly there were other things that it could have been besides the cat.
Fuel trims, exhaust leak, and O2 sensors.
Drove the Jeep for about a year like that trying to rule out everything else before I replaced the cat.
Funny thing was the Jeep seemed to be fine. Just had a CEL.
Was not having any misfire issues or there were no other CEL's or pending CEL's other then the P0432.

So after ruling out everything else best I could I replaced the cat.
Just so happened that I needed a new tail pipe and muffler anyway.
So I just said screw it and replaced the whole exhaust.
With Walker parts and everything has been fine since.

Now here is the rub for you if it is the front cat. Being how you are in NY.
You play by CA rules now if I am not mistaken.
I was able to buy the Walker front cat for a CA Emissions '00 not registered in CA, NY, and now I think ME.
It is cheaper then the one you will have to technically buy because you are in NY.

For instance the front cat for my Jeep was 52304.
I think you will have to buy 81850.
I don't think that an auto parts store in NY could sell you the cheaper cat.
I don't think that RockAuto or Amazon could deliver the cheaper cat to you in NY.
Thinking we are talking about $140 difference in price here.

 

You mean 300 codes? List all the specific codes you're getting.

 

How needed?

Generally, catverts don't like burning antifreeze.

 

What brand of sensors?

Does you tester have the ability to see live data from the oxygen sensors?

 

Codes:
po300
po301-misfire cylinder 1
po302 - misfire cylinder 2
po303 - misfire cylinder 3
po432 - cat
po456 - evap (I think its me not tightening my gas cap because I went through the entire evap system last year)

Well I havent gotten to it, but Im leaking oil from the head gasket been pushing it off but theres no oil in the antifreeze and vice versa.

I went with NTK sensors as Im very search handy and want OEM quality, many people on this forum swear by them. I do not, but I could get a hold of one

 

More codes would be triggered because the pre-cat and post-cat sensors would be reporting the same value. And if NYS analyzes emissions they'd know you disabled the cat (insert debate about going to jail here).

P0432 is a Bank 2 problem but your 300 codes are a Bank 1 problem so it appears you have at least 2 issues.

Is the oil leak from the head gasket an external leak?

 

Generate some oxygen sensor waveforms when you get another tool:



or

 

Did you clear the codes to see if the 300s and gas cap were a transient thing?

 

And for that kind of money they didn't throw in a free cat?

 

But I'm with Ralph on this. Walker cats are inexpensive, if they give you a hassle about being in NY then drive to Greenwich or take the ferry to Bridgeport and get it there. I mean why spend all that money on a fancy exhaust system and leave the part that can be the biggest headache?

 

If you replace the front cat you might want to consider new hardware.
Now I am guessing that hardware store hardware would probably work
But I bought new stuff from my dealership.
The clip nut, goes on the exhaust manifolds, is 6506546AA.

https://www.tascaparts.com/oem-parts...fold-6506546aa

That price is for one. Going to need 4.
The bolts are 6505754AA. Also going to need 4.

https://www.tascaparts.com/oem-parts...head-6505754aa

Don't automatically rule out your dealership for these. Mine is pretty competitive with pricing.
Even when things cost a couple dollars more I will still get it from them.
Always good to have a relationship with your local dealer.
Plus they won't charge you shipping most likely so don't forget to take that into account.

Also remember that your hardware might be just fine too.
Problem with that is you won't find out till you do the job. LOL.

For the back of the front cat to the front of the down/intermediate pipe regular hardware will work.
Flange head bolts or regular ones with washers.

Which brings up another thing.
Is there a separate pipe from the back of the front cat to the front of the back cat on your Jeep?