sgjii

I think my request for assistance may get lost in the thread leading up to diagnosing the bad Pre-Cat assembly.

Short re-cap is P0432 code. Replaced all 4 O2 sensors in hopes of having a "Lazy" sensor issue, but no joy. No exhaust leaks, cracked head, oil burning, coolant burning or other issues so it appears to truly be a Catalyst Below Threshold at 161K miles now on the clock.

I am in Ohio so no California issues of not being allowed to work on my own emissions system. I will stress that I am looking for OEM type repair/replacement/function/performance/emissions and NOT any deletion or modification.

I could not find a write up for removal/re-install of the pre-cat assembly and was wondering if anybody had ideas on the best plan of attack. I currently plan to use the replacement from Eastern Catalytic purchased through RockAuto.

Do either the intake or exhaust manifolds have to come off or can it be removed from the bottom?

Any input would be appreciated.

MichiganCherokee

Should be able to be removed without removing intake and exhaust manifolds. If it were me I'd take it to a muffler shop, have them pull an O2 sensor and use a flexy cam to see if the cats are shot. I haven't heard much on the precats going bad on our 00-01 xjs. Are you getting the symptoms of a bad catalytic converter?

Bustedback

The intake and exhaust manifold do not have come off if the cats bolt onto the manifold.

sgjii

As far as symptoms, the truck runs great and gets decent fuel economy, especially after the new NTK O2 sensors. It is just I get P0432 about once every couple hundred miles if I do in town driving. Having ruled out other sources, I have nothing left but to believe the pre-cat is actually below the 95% efficiency threshold and honestly triggering the CEL and code P0432.

Thanks for the input that it can be done without manifold removals.