Code P0431

[Red Rocker]

So my nieces 05 LJ 4.0 Auto got a P0431 code which from searches shows it could be a bad cat, the exhaust pipes are still in good shape, no leaks.

A couple months ago it had a code for a bad cam sensor and the jeep was running rough on and off for a month, I changed the cam sensor with another made in china OEM Mopar unit and it has been running alright since.
I also replaced it last year with a mopar unit when it came up then too.

So I'm guessing the rough running then and now may have started cooking the cat and now it's finally dead.

I found new exhaust systems on Amazon from flowmaster and magnaflow and some chinesse versions too, prices anywhere from 250 to 750, cheaper ones have kinked tubing on the curves and better ones are mandrel bent around all the curves, cheaper ones have oversized cats while better ones have cats that look oem size.

Don't know what mopar would charge for their replacement if they even offer it

This replaces the exhaust from the manifold to just before the muffler.

Has anyone had to change out there cats and exhaust and found anything that works well for a good price ?

Figure I would replace the O2 sensors too with NGK while I was there.

Any advice or tips or similar problems ?

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[YJScrounge]

I just did a full header back on the yj. I went cheap as it isn't a daily. The pipes were walker. I could have gone cat delete but didn’t. Rig runs great.

Have you tried the additive to clean the cat? I realize most additives are snake oil but could save you the hassle of an exhaust job.

 

[markus68]

check eBay for used OEM....I picked up a fuel tank for 180.00 off a parted out 2018 JK.....also Linders junk yard in MA

 

[XtraChrisP]

I cut the third car out of my exhaust since there are no sensors after it, and it was clogging up on me

 

[Red Rocker]

I cut the third car out of my exhaust since there are no sensors after it, and it was clogging up on me

I saw a kit that just had the 2 first cats and deleted the third which was cheaper than the full system but I was wondering if that was going to have an impact on emissions testing.

Have you gone through emissions testing with yours ?  Did it make any difference on the sniffer test or did they do a visual inspection on the cats ?

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[Red Rocker]

I just did a full header back on the yj. I went cheap as it isn't a daily. The pipes were walker. I could have gone cat delete but didn’t. Rig runs great.

Have you tried the additive to clean the cat? I realize most additives are snake oil but could save you the hassle of an exhaust job.

Where did you get the system from, local or interwebs ?

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[JohnyPro]

The down pipe cats disintegrate after 100xxx or so, I pulled them to replace and they were hollow. That’s most likely your issue. Pull and visually inspect.

 

[JohnyPro]

It was a 04-06 LJ issues from what I’ve seen and heard around.

 

[YJScrounge]

I just did a full header back on the yj. I went cheap as it isn't a daily. The pipes were walker. I could have gone cat delete but didn’t. Rig runs great.

Have you tried the additive to clean the cat? I realize most additives are snake oil but could save you the hassle of an exhaust job.

Where did you get the system from, local or interwebs ?

.

It was either ebay or amazon.

 

[XtraChrisP]

The third cat in LJs is for California emissions only

 

[Red Rocker]

So it turns out it was the Cat that was bad.

Was missing some of the honeycomb material inside.

Changed it with a magnaflow set up, it replaced the pre cats and the new pipe wrapped around the oil pan and started coming down the other side and ended there.

Then I cut the factory pipe where they met up and slipped the factory pipe into the new one and I clamped the two together.

Changed all 4 O2 sensors with new NGK ones while I had it apart.

Took it out for a test ride and all is good for now, hopefully the code won't come back.

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Sent from my SM-G935V using Tapatalk

 

[YJScrounge]

Nailed it!