This happened while I was removing the original oxygen sensor on my SC430. I don't think it's a good idea to install a new one since looking at the sensor thread, it's telling me that there's material left in the groove inside where the sensor screws into.

What do you guys think?

 

I think trying to reinstall one is better than the option of buying a new exhaust manifold...

try to clean up the threads as much as possible, install anti-seize on the new sensor, carefully install...

good luck