should an O2 senson rreplacement accompany a cat converter replacement?

code never identifies a bad part just a failed system. it is up to the tech to determine the failure after evaluating the o2 sensor readings. i dont replace them if they are working correctly. some guys just like to replace them instead of struggling to remove them. Roy

Well a lot of converters are replaced needlessly because of that code, it really should be tested properly before it replaced.