200,000 Mile Club

Read up on performing a Piston Soak.
I have a friend with almost 1 million miles on various Gen 2 and 3 Prii.
He claims to get a big improvement on oil consumption after doing a week long piston soak.

But this all depends on how you deal with the current situation.

Installing a used engine is a roll of the dice. You already have a used engine. You could repair it.

My Gen4 is doing great at 277k miles and doesn't seem to use much oil at all between 5-7k oil changes.

 

So even at OEM prices, a new sensor could be tried first, no??
But your right, that engine has a serious problem that may be too late for a piston soak.

Don't listen to me.
I'm bailing on my '10 w/ 179k miles on it. The head gasket was changed (FelPro) and it runs great. Does not consume oil.
I get the weekly or so P420 for a while now. I'll replace the sensor before selling it.
I'm bailing before the brake booster, or something else goes bad. The pack has always been healthy.
And thanks to The Epstein War, I suspect Prius prices should be on the rise!

Also I get, off hand, 5-7 mpg higher then the Gen3 driving the same with my '19 Eco.
Plus, it's compatible with the Comma4! Big generational jump in tech!