advice about a code?

So I have a 02 Tacoma Prerunner with the V6 motor. Now, this truck has 292,000 miles on it I have done a full motor rebuild mainly because the valve covers were leaking so I replaced almost everything in the motor. I have put so much time and money into getting this girl ready to sell. (I need a diesel for hauling and a bigger truck) Now I live in California, about 3 months before registration was due my check engine light came on. I ran the code and my biggest fear popped onto the screen. P0420 code...if you live in California you know how much of a pain this is. I was so worried it wouldn't pass smog that I ran just about every Catalytic cleaner you can find. With zero luck I get the code to go away. I decided to just clear the code and took it right to the smog shop to my surprise it passed.
Now, I am no expert or anything like that but for these trucks is this common? What other issues could it be?

 

Most common, exhaust leak.

 

https://www.engine-codes.com/p0420_toyota.html

 

Besides both O2 sensors/exhaust leaks

Few other fixes

https://youtu.be/5icTmYItwiE?si=ne_RmzeSKtjMzcxV

 

Wow. That's quite the leap.

Was it an independent shop contracted to the state? If they liked you and the truck maybe they were 'gracious'.

 

I travel a lot for college and work. I was already down to the valve covers it didn't seem reasonable to just do the valves and that was it. I figures it would be worth my time while I had her already open to replace everything else. I did a full tune up and been replacing interior stuff and adding in cosmetic stuff ever sense.

 

Not really, everybody needs a hobby........might as well be a Tacoma


You ever work on a 5.7 tundra......just doing spark plugs takes half a day

 

Oh, you believe it! My hobby is working on my girl every chance I get she getting something new. I am trying to get her to a point where she is bulletproof. Sad to see her have to go but I am needing a newer and bigger truck for work. My next little toy will be a Duramax haha we will see how well that goes I guess. I already know they are a pain to work on.