Will unplugging both upstream O2 sensors help determine if cats are bad?

[Leahatrill]

I’m trying to figure out if my 2 pre-cats are faulty and causing all my codes to appear on my computer. Does anyone know if unplugging the two upstream 02 sensor will help find this out?

im thinking that once unplugged if my Jeep runs better that will indicate that my cats are in fact bad? If it runs the same then it actually means my 02 sensors are bad?

 

[Chris]

No. If you unplug the upstream O2 sensors the vehicle is going to run like complete crap, if it even runs at all.

 

[Leahatrill]

No. If you unplug the upstream O2 sensors the vehicle is going to run like complete crap, if it even runs at all.

Oh really? What about downstream?

 

[Chris]

Oh really? What about downstream?

The vehicle can run just fine without downstream O2 sensors. It will throw a check engine light, but it won't have any affect on how it runs.