You asked about the hot O2 sensor, the upstream sensor has a heating element. I believe your upstream sensors are heated to 800 degrees.
I suspect your success will be short-lived, you will get the MIL, fouled plugs, and terrible gas mileage. The downstream sensor that is hanging in free air will sense a lean condition and enrich the fuel mixture.

 

Downstream only monitors cat efficiency. The upstream controls the fuel trims

 

As noted, the DS O2 is just to confirm the cat is working... an anti-fouler will do the fooling just fine.

There are O2 simulators that plug in to return a signal like the sensor is happy (Google search will get you examples, and YouTube will get you how to make your own).

I don’t know what that would do on an US O2 that is used to control mixture.

 

If you put a simulator in place of the front O2, the engine would run, but, gas mileage would suffer, and likely other performance problems as well. Also would need to do something for the heater circuit, otherwise, you would get codes about it.

 

Hey I would do as this video shows you. You just need to purchase the spark plug fouler (heh O2 sensor fouler). I put in a a small piece of stainless wool inside the fouler plug. I've gotten rid of my cat years ago by doing this, with no cel's. I just cut the front off the cat, and welded in a new chunk of 3in exhaust. I also cut the rear O2 sensor nut out and welded it back into the new chunk of exhaust. Heck you could even run 4in exhaust and really open up the exhaust. I have a spare exhaust off a newer dodge diesel from a previous project.


Just weld in the plug on the top side of the pipe, as the bottom will fail due to moisture collection.