2002 3.4 V6 Need new Catalytic converter(s?) - recommendations?

Newbie here, first post. I have 2002 3.4 V6 and been slowly working it back to snuff, brother gifted me since it was wrecked a few years back and needed lots of work.
Now it's my daily driver after my car was recently stolen.

Anyways,
its throwing codes for Cat on my ODBII , and I can't tell if just needs the front or both. The code doesn't seem to specify. So I'll go ahead and replace both. Truck has 188K miles and I've redone all the engine seals so it should have some longevity left.

I am told they discontinued Cats so now they only make aftermarket. I am looking at rockauto and Ive seen Walker recommended on these boards so, Im noticing they have a 52297 model for $254 or 81740 model for $674. And similar for the rear cat.

My question for you expert is... is there a worthwhile difference in the performance of these? Or is there another supplier or maker you'd recommend altogether? Thank you!!

 

Do you live in a state the requires them? Some have deleted the cats altogether. They run O2 sensor spacers to keep the computer happy. The spacers may be a good option regardless of which cats you decide to go with if they throw codes as aftermarket cats often do with Toyotas.

 

Cat efficiency is measured by downstream H2OS sensor. It's life span is around 100-150k miles. Have all H2OS sensors replaced first and then see if the cats are actually dead. They are usually not, unless the engine was gulping oil and/or had air-fuel mixture or ignition problems.

 

Ok, thank you, I was considering this but had been told that if you don't replace cats it will eventually damage things.

Yes, It was first throwing code for 02 sensor so I replaced that and now its just throwing the Cat code

 

Which one? It has two for every head. Upstream sensor (closest to exhaust manifold) takes part in air-fuel ratio correction, downstream evaluates the cat's health.

 

P0420
Control Unit: 10
Catalytic Converter System Bank 1 efficiency Below Threshold


This is the exact trouble code as it shows now

 

I mean, which sensor you replaced? You actually need both sensors working properly.

 

That's your Mass Airflow Sensor, or MAF. That code is for an O2 sensor. They are located on the exhaust side, not the intake side.

 

This is MAF, not H2OS.

 

Yes, that was the one throwing code, so I replaced, and now I just get the cat code I mentioned.

 

If you are willing to take off you exhaust, you could use inspection camera and a light and check how the converter's mesh is doing. If it's not melted, it is good. Bolt it back on.

 

Buy all 4 new H2OS sensors and replace your old ones. 90%+ of confidence the code will go away and the truck will be generally more responsive and even consume less fuel.

 

Just one upstream and one downstream… so 2 new sensors… unless I’m crazy/blind?

 

For each cylinder head. V engines typically have 2 cylinder heads =)

 

Make sure you only use denso O2 sensors

 

Update:
I replaced with Denso upstream and Downstream sensors ordered from rock auto.
Only 1 of each for the 2002 V6 3.4L
Soaked the nuts with PB'Blaster the day before and was not too hard getting them off.

I ordered replacement nuts since they were pretty raggedy looking
Part number is: 90179-08059 and was able to find them on parts.elmhursttoyota.com for a buck or two each instead of the 10 bucks each you'd have to pay on Amazon.

I Cleared the ODBII codes, check engine light is off and the fuel economy seems to have improved as well as the engine seems to run a little quieter and smoother now.


Thanks for all the advices!